2014 biology notes

7/23/2019 2014 Biology Notes

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BIOLOGY MASTER NOTES [PRELIM + HSC] SUMMARY

CHAPTER 1: A LOCAL ECOSYSTEM

1.1 TERRESTRIAL AND AQUATIC ENVIRONMENTS

• An ecosystem is any environment containing living organisms interactingwith each other and with the non-living parts of that environment. It can be

any size or any area.

• Environments have abiotic and biotic factors, or non-living, and living factors.

• The habitat of an organism is where it lives.

• A group of organisms found living in together in one place is called a

community.

• Ecology is the study of the relationships living things have with each other

and their environment.

• Terrestrial environments are environments on land; auatic environments are

environments in water, salt or fresh.

ABIOTIC CHARACTERISTICS INCLUDE:

• Viscosi! ! a measure of how hard it is to move through a gas or liuid.

"ater has high viscosity, ma#ing it harder to move through. Air has low

viscosity, ma#ing it easier to move through.

• B"o!#$c! ! the amount of support e$perienced by an ob%ect immersed in

liuid or gas. "ater provides support to both animals and plants, helping

them maintain their shape and functions. Air does not provide buoyancy, and

organisms must support themselves.

• T%&'%(#"(% V#(i#io$ ! "ater heats up slower than air, this temperature

and the ability to avoid or tolerate heat loss is important to organisms.

• P(%ss"(% V#(i#io$ ! The earth&s gravitational 'eld gives rise to di(erent

pressures in air and water. )ressure increases rapidly in water due to depth.

*n land pressure +uctuates, sometimes a(ecting breathing and +ight of

animals

• A)#i*#i*i! o, -#s%s ! * and * are important for living organisms. In

water, gas availability is low, depending on temp. i(usion is slower and

more gases can be dissolved at lower temps. *$ygen availability a(ects

distribution of organisms and their body structure.

• Io$ #)#i*#i*i! ! Ion/ An atom or molecule with a net electric charge due to

the loss or gain of one or more electrons. *rganisms need to be able to copewith osmotic di(erences in their cells and the environment. 0altwater

environments contain 1.23 sodium and chloride ions, whereas freshwater has

low ion concentration. Ions are available in soils depending on composition,

in+uencing type and plant growth.

)at 4ussell ! 0t 5rancis 6avier ollege



• Li- #)#i*#i*i! ! Auatic may be re+ected scattered or absorbed,

decreasing rapidly in depth a(ecting organism distribution. Terrestrial light

passes easily through air, plenty of light available.

POPULATION

• Dis(i"io$ ! "7E4E a species is found

• A"$/#$c% ! 7*" 8A9: of the species live in an ecosystem

• Dis(i"io$ and abundance are both a(ected by biotic and Abiotic factors

• To measure distribution, we can s#etch the area, or more commonly use a

transect, recording organisms found across the 'eld in line with a narrow strip

of area.

• To measure abundance, we can count all of a species in an area, or through

the use of two methods/ 4andom uadrat, and capture recapture.

• R#/o& Q"#/(# ! sed to record abundance of plants and slow-moving

organisms such as medulla and periwin#les. It involves placing a uadrat

suare randomly in the chosen area, and recording how many organisms arefound in that uadrat. This is repeated many times and the total number of

organisms found in the combined uadrats is compared to the size of the

study area to determine the abundance.

• C#'"(% R%-C#'"(% ! sed when species studied is constantly moving. It

involves capturing and tagging, or mar#ing, a sample of animals, say 2, and

then releasing then. Then return bac# to the same site later on and

<recapture= a sample, say >?, a count how many previously tagged animals

are in the new sample. Abundance is calculated through the euation/

A"$/#$c% 0 $"&%( c#'"(%/ $"&%( (%c#'"(%/2$"&%( &#(3%/

i$ (%c#'"(%/

PHOTOSYNTHESIS AND RESPIRATION

)hotosynthesis is the process by which plant cells capture sun energy and

combine it with * and 7* to ma#e sugars and o$ygen.

4espiration is the process by which cells obtain energy through the brea#ing

down of organic molecules, particularly sugars to produce * and 7*,

releasing energy.

These processes are related because energy from the sun is incorporated into

the products of photosynthesis, used by plants. "hen these plants are

consumed, the organism obtains nutrients used in respiration so that they toocan obtain energy. This energy drives the metabolic processes in an animal

and ultimately drives ecosystems

PS 4 THE EQUATION 0 CO5 + 6ATERLIGHT +

CHLOROPHYLLSUGAR + O7YGEN

CR 0 GLUCOSE + O7YGEN 8 CO5 + 6ATER + ENERGY

AEROBIC CELLULAR RESPIRATION




Involved a series of chemical reactions, releasing small amounts of energy

into the bond of organic molecules, such as sugar. This energy is then

released when the bonds are bro#en, which is then transferred to AT).

8ost AT) originates from the cellular organelle, 8itochondrion.

• Energy from respiration is used inside the organism, such as heat, growth,

and repair.

1.5 LOCAL ECOSYSTEMS: INTERACTIONS AND RESPONSES

RELATIONSHIPS BET6EEN ORGANISMS IN THE SAME ECOSYSTEM

• The relationships between organisms in an ecosystem can be comple$,

however they usually adhere to one of the following common relationships/

• P(%/#io$ ! A feeding relationship where one animal, the predator, #ills and

eats another animal, its prey. Also #nown as a predator-prey relationship it

can vastly e(ect population numbers in an ecosystem, with rises and falls of

predators usually following rises and falls of prey.

• A**%*o'#! ! The production of chemicals by a plant that can have good or

bad e(ects on the plants surrounding it, in+uencing growth and development

of neighboring plants for good, i.e. repelling parasites and predators, or bad,

i.e. poisoning or hindering the other plants.

• P#(#siis& ! "here one organism obtains food from another, harming the

host in some way but not always #illing it. 8ost free living organisms have

parasites.

• Co&&%$s#*is& ! "here one species bene'ts o( another, but does not harm

it. 0uch as the remora and the shar#.• M""#*is& ! @oth species bene't from each other, such as the ringtail

possum and the bottlebrush tree. 4ingtail gets food, whilst it&s dropping

encourage growth of the tree.

BIOMASS AND ENERGY PYRAMIDS

@iomass is the amount of living material in an organism or group of

organisms at one time.

@ecause plants are producers, their biomass is the greatest in the chain, with

it slowly decreasing as it moves through the trophic levels.

5or this reason, herbivores generally have a greater biomass than carnivores.

0imilarly to @iomass, E9E4: is also lost as it moves up the trophic levels.

This loss is shown by an energy pyramid, which loo#s very similar to a

biomass pyramid as energy is transferred in food that ma#es up the biomass.

The further along in the food chain the organism is, the less energy is

available to it.

• Energy is lost in a number of ways, usually though heat, growth, and as feces

or urine.




ADAPTATIONS

An adaptation is a feature of an organism that ma#es it well suited to its

environment and lifestyle, it can be structural, physiological, or behavioral.

Adaptations help an organism to survive and reproduce in its ecosystem

•

They are inherited characteristics, a result of natural selection.

CHAPTER 5: PATTERNS IN NATURE

5.1 ORGANISMS: CELLS AND THEIR STRUCTURE

THE CELL THEORY

• All life forms are made up of units called cells, the building bloc#s of which all

living organisms are made.

• The cell theory states that/ ells are the smallest units of life, All living things

are made up of cells, and all cells come from pre-e$isting cells.

HISTORICAL DEVELOPMENT

• The development of the cell theory went hand in hand with technological

advances, particularly of lenses and magni'cation devices, such as

microscopes, in the >Bth century, enabling much greater detail to be seen.

• The 'rst recorded study of cells was in the >Cth century by 4obert 7oo#e, who

used his home-made microscope to view a thin piece of cor#, and identi'ed

the nucleus as a large body found inside cells.

•

*ther notable scientists who helped develop the cell theory areDeeuwenhoe#, who described unicellular organisms from rainwater as

animalcules& and discovered bacteria in his saliva. And 4obert @rown, who

noted how cells have a common structure inside the cell, he named it the

nucleus.

TECHNOLOGICAL ADVANCES

• The light microscope, used e$clusively until >B11, allowed cells to be visible

to some degree, aided by the use of staining to able us to see some parts of

the cell, such as the nucleus, the cell wall, and due to absorption of stain, the

chromosomes.• In >B11, Ernst 4us#a built the 'rst electron microscope, enabling more

detailed observations of all structures to be made.

• "hilst electron microscopes allow much more detail to be shown, they are

e$pensive, ta#e time to prepare, and can only view non living sections.

THE STRUCTURE O9 CELLS




Although ells show great variation, they have certain structures in common

All cells have a clearly de'ned shape or boundary, maintained by a cell

membrane, which encloses the internal contents of a cell.

Inside, cells contain a number of organelles, which each have a particular %ob

to do for the cell.

• ells visible with a light microscope include/ the nucleus, the cell membrane,cytoplasm, cell wall, chloroplasts, and the vacuoles.

CELL STRUCTURES AND THEIR 9UNCTION VISIBLE 6ITH A LIGHT

MICROSCOPE:

N"c*%"s ! ontains the chromosomes, which controls the development and

function of the cell. "ithout the nucleus, the cell will die.

C%** &%&(#$% ! 5orms the boundary between the cytoplasm and outside

environment, controls entry and e$it Fdi(usionGosmosisH of substances to and

from the cell

C!o'*#s& ! ontains many organelles and is where most cell activities arecarried out

C%** #** ! ives protection, support and shape. 5ound in all plant cells.

C*o(o'*#ss ! ontains chlorophyll and are the site of photosynthesis in

plants

• V#c"o*% ! 0tore water and other substances, large and important in plant

cells.

• nder an electron microscope, these features are available in higher detail,

and other organelles can be seen. These include the mitochondrion, the

ribosome, and the olgi body.

6HAT THESE ORGANELLES DO 9OR A CELL

• Mioco$/(io$ ! omposed of folded layers of membrane, it&s involved in

the energy transformations in cells

• Rioso&% ! 0ites of production of proteins in a cell

• Go*-i Bo/! ! A stac# of +at membrane where 'nal synthesis and pac#aging

of protein occurs before secretion

CELL STRUCTURES IN DETAIL

N"c*%"s ! 0pherical and large compared to other cell structures. ontrols the

activities of the cell by dictating which proteins are made. ontains the mostgenetic material in the cell, containing chromosomes, which in turn contain

genes, the inherited information that determines whether proteins are made

or not. The nucleolus, in the nucleus on non-dividing cells, is where genes for

49A are found.

Mioco$/(i# ! sually ?.2 micrometres wide and C micrometers long. They

are surrounded by a double membrane, with the inner being greatly folded,




greatly increasing the surface area for the chemical reactions of respiration to

occur.

L!soso&%s ! 0mall membrane-bound organelles common in animal cells but

rare in plants. They are very acidic, containing digestive enzymes to brea#

down or digest old or damaged organelles.

E$/o'*#s&ic R%ic"*"& ! A system of membranous sacs and tubulesconnected to the nuclear envelope. It provides an internal surface for many

chemical reactions in the cell, and a series of channels through which

material can be circulated. 4ough End. 4et. has tiny ribosomes attached

where proteins are made an transported to the olgi body in transport

vesicles. 0mooth has no ribosomes and is the site for lipid manufacture.

Rioso&%s ! Tiny bodies made up of 49A and protein which may be

attached to endoplasmic reticulum or lie freely in the cytoplasm. They are the

site of protein manufacture

Go*-i o/! ! 0tac#s of +attened membrane sacs, which chemically modi'es

and stores and distributes substances made by the endoplasmic reticulum.

These are received in transport vesicles and repac#aged, ready for secretion

either into or out of the cell.

• C*o(o'*#ss ! *nly found in plant cells, they are surrounded by a double

membrane and contain a comple$ system of lamellae. )hotosynthetic

lamellae also called thyla#oids occur in stac#s called grana, which contain the

chlorophyll pigments needed for photosynthesis.

5.5 S;IPPED: THE SUBSTANCES IN CELLS

THE MOVEMENT O9 MOLECULES




The +uid mosaic model shows how a cell can be selectively permeable and

how di(usion and osmosis can occur.

• i(usion is one way cells ta#e in materials from the environment, and a way

of ridding unwanted materials, such as waste. i(usion will occur when two

areas have a di(erent concentration of a substance, moving until euality is

reached. 9ot all substances can move through cell membranes due to size.

"ater, *, and * and other small ions and molecules can move freely.

•*smosis is li#e di(usion, but only applies to water. "ater will move from ahigh concentration to a low concentration. This is how water leaves and

enters cells.

SUR9ACE AREA TO VOLUME RATIO

A new cell beginning to grow receives nutrients through its surface

membrane

The area of this surface a(ects the rate at which nutrients can enter the cell,

as well as the rate at which wastes can leave

As the cell grows, its needs are greater, however due to the 0urface Area to

olume 4atio, its e$change of material falls

0o as the cells increases in size, its surface are to volume ratio gets smaller,

meaning it can ta#e in less nutrients and e$pel less wastes

@ecause of this, cells can only grow to a certain size, otherwise it would be

unable to survive

5.< OBTAINING NUTRIENTS




CELLS AND SYSTEMS

• In multi cellular organisms, di(erent cells may have di(erent functions, each

wor#ing together for the organism as a whole.

roups of cells similar in function are called tissues, and groups of tissues

ma#e up organs, which in turn ma#e up the systems within the body. Eg.igestive system in humans.

• There is no such thing as a typical cell, however they can be generally

identi'ed as autotrophic, meaning self-feeding& FplantsH, and heterotrophic,

meaning feeding on something di(erent& FanimalsH

PHOTOSYNTHESIS

• )hotosynthesis can only occur if plant cells can obtain *, 7*, and light

from its environment.

• All living things depend on this process as if provides chemical energy for

each living thing.• "ithout photosynthesis, there would be no energy to sustain life.

THE EQUATION 0 CO5 + 6ATER LIGHT + CHLOROPHYLLSUGAR +

O7YGEN

0unlight is absorbed by chlorophyll pigments in the chloroplasts of green

plant cells, and is turned into usable, chemical energy.

0ugar products from photosynthesis are converted to starch and stored in the

cells, causing a green leaf to turn blueGblac# when e$posed to iodine solution

Fstarch testH

• These sugars are also used in respiration in the plant, being converted bac#

into sugars at night and transported by the phloem to the rest of the plant.

nused sugars may also be built up into proteins for growth, of be stored asstarch or lipid.

OBTAINING NUTRIENTS = PLANTS

6ATER AND MINERALS

• )lants use specialised structures to obtain the materials reuired for

photosynthesis from their environment.

• nless it is an auatic plant, most water and minerals are obtained though

root systems with a large surface area, which also act as an anchor

• There are two main types of roots; tap roots; and 'brous roots.• The roots growing point is protected by a root cap, and %ust behind this point

is the region of root hairs, which provide a larger surface area where most

absorption of water and mineral ions ta#es place

OBTAINING SUNLIGHT AND CO5




• The specialised structure for obtaining light and * in most plants is the

leaf, which is where most photosynthesis occurs

• Arrangement of leaves, shape, and size are all factors and adaptations leaves

have to ensure they receive the most sunlight and *, usually being

arranged in a way to receive the most sunlight, and broad and +at to increase

surface area.• The plant has a number of internal structures, each related, and important to

the process of photosynthesis

INTERNAL STRUCTURES O9 A LEA9

• C"ic*% ! A wa$y substance on the surface of the leaf which maintains shape,

provides protection, and reduces water loss due to evaporation.

• E'i/%(&is ! )rotective layer of cells on the upper and lower surfaces,

transparent so can be easily penetrated by sunlight to the photosynthetic

cells within

• So&#%s ! )ores in the leaf that can open and close to e$change gasesbetween the leaf and the environment. This process allows water to

evaporate, which is why they close.

• P#*is#/% M%so'!** ! 5ound one or two rows below the upper epidermis.

They are regularly arranged, elongated cells pac#ed with chloroplasts. This is

where most photosynthesis occursJ

• S'o$-! M%so'!** ! 5ound between the )al. 8es. and the lower epidermis.

ontain fewer chloroplasts and are irregularly arranged to allow the

movement of gases and water to the cells and stomates

• V%i$s ! Tubes of vascular tissues containing )hloem and 6ylem cells, which

transport materials to and from the leaf. 6ylem transports water and mineral

ions from the roots to the leaves, where as )hloem transports the products of

photosynthesis from the leaves to the rest of the plant. eins form a

branching networ#, giving rigidity, maintaining shape and structure, and




ensuring every leaf cell is close to a vein.

MAMMALIAN DIGESTION

THE DIGESTIVE SYSTEM

Animal cells are heterotrophic, so they cannot ma#e their own food, and must

obtain it from somewhere else.

The digestive system allows nutrients to be ta#en into the organism and

bro#en down and digested, converting large insoluble food molecules into

small, soluble ones that can be absorbed and made available to the cells.

• In mammals, digestion involves both mechanical, and chemical brea#down of

food by enzymes, followed by absorption into the body

HERBIVORES AND CARNIVORES COMPARED = MOUTH AND TEETH

• The action of teeth greatly increases the surface area of food, allowing them

to be bro#en down and absorbed faster

• 8ammals have K #inds of teeth, incisors and canines, used for cutting

Fprominent in carnivoresH, and molars and premolars, used for grinding

Fprominent in herbivoresH.

9EATURES O9 THE HUMAN DIGESTIVE SYSTEM




Mo" #$/ &o" c#)i! ! Teeth mechanically brea# food into pieces,

saliva lubricates food

E'i-*ois ! loses of the trachea so food goes down the oesophagus Fnot

the windpipeH

O%so'#-"s ! arries food to stomach

So&#c ! @egins the digestion of proteins and the food is churned. Thelength of time food spends in the stomach is related to diet. arnivores have

simple stomachs, whereas herbivores may have comple$ stomachs with food

remaining there for a long time

P#$c(%#s ! )roduces enzymes and neutralises acid

Li)%( ! )roduced bile which emulsi'es fats, and stores some products of

digestion

G#** B*#//%( ! 0tores bile

S&#** i$%si$% ! igestion is completed by enzymes from the pancreas and

the small intestine itself. 9utrients and water are absorbed

L#(-% i$%si$% ! "ater is absorbed with soluble compounds li#e vitamins

and minerals. ndigested food leaves body as feces. The c#%c"& is found

here, which is enlarged in herbivores as it is where bacterial fermentation of

plant material occurs. arnivores have a small c#%c"& and a shorter large

intestine as their food reuires little fermentation

5.> E7CHANGING GASES

GAS E7CHANGE IN ANIMALS

• All organisms respire, ta#ing o$ygen from the environment and releasing *

through the use of respiratory surfaces

• These surfaces must be thin, moist, and have a large surface area to allow

easy di(usion

INSECTS




• Insects have a system of tubes called (#c%#% within their body

• These tracheae open to the e$ternal environment through pores, or spiracles,

on the abdomen, allowing gas to be e$changed throughout the insect&s body,

bringing air directly to the cells

• The ending of the tracheae are called tracheoles and usually are 'lled with

+uid

9ISH

• 4espiratory surface is gills over which water +ows

• Two types/ e$posed and those covered by an operculum

• sually 'nely divided which means water +ows over a large surface area.

9ROGS

• Two respiratory surfaces ! Dungs and s#in

• *$ygen from air di(uses into moist s#in and is transported by blood to the

heart and then around the body

• Dungs are simple and have a smaller surface area than mammals, are more

li#e balloons than sponges and are less eLcient that mammalian lungs

MAMMALS

• ases e$changed in the lungs

• Dungs are protected by being inside the body&s waterproof covering

• 0urface area of lungs is increased by the convolution of the lungs into lobes,

the branching of the bronchioles, and the division of the tubules into tiny air

sacs called alveoli.

TRANSPORT SYSTEMS IN 9LO6ERING PLANTS

THE NEED 9OR TRANSPORT SYSTEMS

• Transport systems are used to ensure that cells are supplied with nutrients

and to e$pel waste.

• 8ulticellular organisms have these systems, enabling substances to be

moved to and from the internal body cells

• In +owering plants, long tubes run through the root, stem, and leaves. These

are the $ylem and phloem which each transport a di(erent substance

• "ater and minerals are transported up the plant in the $ylem and organicmaterials are transported both up and down by the phloem

6ATER TRANSPORT

• "ater and mineral ions +ow upwards through the plant, starting at the roots

and lost by transpiration




• The root hairs provide a large surface area for the upta#es of water, entering

by osmosis through the centre of the root and moving to the $ylem

• 6ylem vessels are dead cells thic#ened with woody material which form a

continuous system of tubes, giving strength ad rigidity to the stem. "ater

moves up the $ylem aided by conducting cells and is transported to the

leaves via the stem• The di(usion of water from a plant is called transpiration

• This occurs when the stomates open to e$change gases as the water di(uses

out due to uneven water concentrations of the plant and e$ternal

environment

• E$ternal factors which can a(ect transpiration include temperature, humidity,

wind, light, and soil

PHLOEM

• Transports sugars produced in photosynthesis around the plant

• 8aterials are transported both up and down the plant.

GASEOUS E7CHANGE IN PLANTS

STOMATES

• 0tomates are pores in leaves through ehich gases can di(use

• sually found on the lower surface of a leaf

• an open and close, determining whether gases can disuse or not, which in

turn a(ects the rate of photosynthesis and the transpiration rate

• uard cells control this opening and closing, becoming full of water, or turgid,

to open and losing water to close• 0tomates are usually open during the day and closed at night however guard

cells respond to a variety of di(erent internal and e$ternal stimuli, including/

light, low carbon dio$ide levels, an internal cloc#, water de'ciency, and high

temperatures

5.? GRO6TH AND REPAIR

MITOSIS

• 8itosois is the process by which a multicellular organism grows, repairs,

maintains, and reproduces itself

• It is a type of cell division that results in the production of cells which are

identical to the original

• It really ta#es place in two separate processes ! 8itosis, division of the

9ucleus, and yto#inesis, division of the cytoplasm

• )rior to mitosis, the cell&s KM chromosomes are copied, which are the

distributed during mitosis into each new cell as it forms




THE STAGES O9 MITOSIS

• Interphase ! The period when cells are not dividing, chromosomes are

duplicating, but not visible

• )rophase ! Each chromosome visible as two identical %oined strands called

chromatids. The nuclear membrane brea#s down by late prophase• 8etaphase ! 8icrotubles spread across the cell forming a spindle. The

chromosomes line up at the centre of the cell attached to the spindle 'bres at

the centromere. The chromatids separate

• Anaphase ! The chromatids, now single stranded chromosomes move

towards opposite poles, carried by the spindle 'bres

• Telophase ! The spindle disappears and new nuclear membranes form around

the two sets of chromosomes

•

THE NEED 9OR CYTO;INESIS

• yto#inesis usually happens immediately after mitosis, ensuring the

chromosome number in each cell remains constant

• The chromosome number doubles in mitosis and one cell now contains sets

of chromosomes, reuiring yto#inesis to occur so as to create two cells

SITES O9 MITOSIS

PLANTS




• In mature plants, mitosis mostly occurs in the tips of roots and stems, causing

an increase in length. It occurs in other places too but we don&t need to #now

that

INSECTS

• Instead of cell division FmitosisH, insects grow through cell enlargement and

therefore there are no sites of mitosis

MAMMALS

• In young mammals, mitosis rates are high and occurs in all areas of the body

• At maturity, growth decreases but the repair and maintenance of cells

continues

• In adults, it occurs in the s#in, bone marrow, and digestive system constantly

CHAPTER <: LI9E ON EARTH

<.1 THE ORIGINS O9 LI9E

THE PRIMEVAL EARTH

• There are ma%or theories on how life could have started on earth

PANSPERMIA

• The theory of )anspermia states that the chemicals for life came from outer

space

• 0cientists believe that the earth was heavily bombarded with meteorites

during the early years of formation

• "hen certain types of meteorites in the >BC?s were analysed, they were

found to contain organic molecules such as amino acids, the building bloc#s

for life

• This provided evidence of the e$istence of organic molecules somewhere else

in the cosmos and shows how meteorites falling on earth during it&s early

formation could have contributed to some of the organic molecules reuired

by living systems

CHEMOSYNTHETIC 9ORMATION ON EARTH

• 5irst suggested by *parin and 7aldene, who theorized that the early

atmosphere of earth contained all the necessary chemical components for life

to form, hypothesizing that more comple$ organic molecules, such as Amino

Acids, could have been created in spontaneous reactions using energy from

4ays or lightning.

• 7owever, this theory remained untested until the >B2?s when two scientists,

rey and 8iller, performed an e$periment based on the hypothesis




• A closed system was set up and powerful electrical spar#s Fsimulating

lightningH were discharged into a chamber containing ammonia, hydrogen,

and methane; three gases thought to have been prominent in the early

atmosphere

• After a wee# of continuous discharges and recycling of steam, the condensed

water in the +as# set up under the e$periment became red and turbid, andfound to contain a number of amino acids

• This supported *parin and 7aldene&s theories and showed how organic

molecules could have formed naturally in the conditions of early earth

CHANGES IN TECHNOLOGY

• *ur ability to describe the origins, processes, and evolution of living this has

been made possible in advances in science and technology, with new

techniues to 'nd more about earth, it&s history, and the living organisms

that occupy it bring developed

• The most important in the study of early earth is the development ofradiometric dating, which allows scientists to determine the age of roc#s and

fossils bac# to the formation of earth

• evelopment of the electron microscope has also played an in+uential role in

the #nowledge of cells and their structure and function, enabling scientists to

compare di(erent organisms and see how they function

• These new technologies lead to a better understanding of the origins of life

and the evolution of living things

<.5 9OSSILS AND THE EVOLUTION O9 LI9E

MA@OR STAGES IN THE EVOLUTION O9 LI9E

>. The formation of organic molecules. The formation of membranes1. )rocaryotic cells ! 0imple structuresK. Eucaryotic organisms ! 9ucleus and organelles developed2. olonial cells ! 5ound in stromatalitesM. 8ulticellular organisms ! 0how specialization of function evolved

PALAEONTOLOGICAL AND GEOLOGICAL EVIDENCE O9 EARLY LI9E

PALAEONTOLOGICAL EVIDENCE

• Evidence of early life can be found in fossils however is scarce compared to

over the past M?? years

• Earliest fossils are found in two types/ microfossils, and stromatalites which

are layered mats of photosynthetic pro#aryotic cells called cyanobacteria

• escendents of these cyanobacteria can still be found in "estern Australia

• These fossils can be found in roc#s over 1K?? million years old




GEOLOGICAL EVIDENCE

• The 'rst cells were heterotrophic, however as the developed they gained

pigments and were able to capture light energy from the sun and use it to

convert * into o$ygen

•

As more photosynthetic organisms developed, more * was converted into*$ygen, which started to be ta#en up by roc#s

• These o$idized roc#s can be seen in banded iron formations and red bed roc#

formations today

S;IPPED: THE CHANGING ATMOSPHERE

<.< PROCARYOTES: THE 9IRST LIVING THINGS

6HAT ARE PROCARYOTIC ORGANISMS

• @elieved to be the 'rst type of cells to evolve on Earth about 1?2? million

years ago• 0till the most abundant life form on earth

• i(er from eu#aryotic cells as they lac# a nuclear membrane and internal

organelles

• Technological advances in electron microscopy have increased our #nowledge

of pro#aryotic organisms, such as the discovery of two di(erent types of

pro#aryotes/ Archaea and Eubacteria

<.> TA7ONOMY: CLASSI9YING ORGANISMS

6HY CLASSI9Y

• lassi'cation systems help biologists to understand the relationship between

organism, and to tal# to other biologists about organisms without the need to

describe them in detail

9EATURES USED TO CLASSI9Y ORGANISMS

• Anatomy FstructureH, physiology FfunctioningH, behavior FdoingH, and

biochemistry Fmolecular activityH are the ways organisms can di(er, and

using these features as a guideline, biologists can easily classify organisms

• The most practical in the 'eld is anatomical structure, as it is easily observed

and more constant in an organisms lifetime• 7owever structure is not always reliable, as organisms which loo# the same

may not always be closely related, for this reason the molecular structure, or

9A, is increasingly being used by biologists to classify organism

CLASSI9ICATION SYSTEMS

The most common classi'cation system recognizes 2 #ingdoms/




• )lants ! organisms which contain chlorophyll and ma#e their own food.

Eucaryotic and have a cell wall

• Animals ! o not contain chlorophyll, cannot ma#e own food, eu#aryotic, no

cell wall

• )rotists ! 0ingle celled, eu#aryotic Feg. )rotozoansH

• 8onera ! 0ingle celled, pro#aryotic Feg. @acteriaH• 5ungi ! o not contain chlorophyll, eu#aryotic, surrounded by a cellulose cell

wall

LEVELS O9 ORGANISATION

*nce Ningdom is determined, there are M other levels in which an organism is

classi'ed. These are/ )hylum, lass, *rder, 5amily, enus, and 0pecies

ADVANCES THROUGH TECHNOLOGY

• evelopment on light and electron microscopes dramatically in+uenced

scientist&s ability to view cells and di(erentiate and classify organisms

• Advances in molecular biology and biochemistry aided in the discovery of the

two main groups of 8onera F)rocaryoticGEucaryoticH

• 9A and molecular comparison tec$hniues to accurate classify organisms

based on their genetic structure rather than appearance, adding to out

#nowledge of relationships between organisms and helping to re'ne the

classi'cation system

THE BINOMIAL SYSTEM

• This classi'es organisms with two given names, the 'rst being the enus,

and the second being the 0pecies of the organism

• enus always starts with a capital and species always starts with a lowercase

Feg. @an#sia coccineaH

S;IPPED: DICOTOMOUS ;EYS

CLASSI9YING E7TINCT ORGANISMS

• 5ossil remains are not always diLcult to classify, however problems arise

when the fossil is incomplete or does not show enough detail to accurately

assess the structure of the organism

• )roblems also arise if the organism has been e$tinct for a long time as theremay be no similar organisms alive today to compare it with

CHAPTER >: EVOLUTION O9 AUSTRALIAN BIOTA

>.1 GOND6ANA: ANCIENT SUPERCONTINENT

THE 9ORMATION O9 AUSTRALIA




• Australia became a separate continent K2 million years ago, splitting o( from

ondawana, which in turn split o( from )angea, an ancient supercontinent

about >M? million years ago

GEOLOGICAL EVIDENCE

• The roc# strata around the continental margins, match perfectly in many

places, such as between 0outh Australia and one section of Antarctica

• The ages of roc#s near mid-ocean ridges indicates a continual movement of

the plates, as the closer to the ridge, the younger the roc# is

BIOLOGICAL EVIDENCE

• 5ossil evidence shows similar organisms on continents thought to be part of

ondwana as those found in Australia

• Diving species are also similar in some parts of the world which are believed

to be part of ondwana, particularly southern beech trees, found in Aust, 9O,

9ew uinea, and 0th America

AUSTRALIAS MEGA9AUNA

• In simple terms, megafauna are large animals which have mostly all gone

e$tinct over the last 2???? years, apart from such animals as the elephant

and whales

• There are two main theories to e$plain this rapid e$tinction/

• limate change/ 8uch e$tinction occurred at about the end of the last Ice

age, an event which drastically changed the ecosystem. In Australia, the

weather changed from cold and dry to warm and dry, meaning the water

became scarce and unable to sustain life for such large animals

• 7uman e$pansion/ The megafauna were big and slow, therefore vulnerable to

hunting, in particular the arrival of s#illed hunters. It is thought that the rapid

e$tinction of many Australian megafauna occurred soon after humans arrived

in Australia for the 'rst time

• It is li#ely that both these factors played a part in the e$tinction of these

species

• Today, relatives of the megafauna survive, such as the red #angaroo to the

Procoptodon pusio and the Diprotodon optatum to the wombat

• The megafauna were not descendants of Australia&s current fauna however,

they both evolved from a common ancestor

>.5 CHANGES IN AUSTRALIAN 9LORA AND 9AUNA

VARIATION 6ITHIN A SPECIES

• ariations are small di(erences between organisms belonging to the same

species




• This can include di(erences in size and colour, as well as biochemical

di(erences

• These di(erences become important in evolutionary terms as when

environmental change occurs, those with di(erent variations may be able to

survive

S;IPPED: AUSTRALIAS CHANGING ENVIRONEMENT THE AUSTRALIAN

ENVIRONMENT CHANGES IN THE DISTRIBUTION O9 SPECIES

CHARLES DAR6IN IN AUSTRALIA

• "hilst in Australia, arwin was puzzled over the variety of organisms present

in Australia, spending a long time studying them

• @y comparing species found in Australia to those found in England and 0outh

Africa, arwin supported his theory that new species of an organism can

develop from a common ancestor and that those best suited to the

environment were more li#ely to survive and prosper

>.< THE CONTINUATION O9 A SPECIES

MEIOSIS

• 8eiosis is a type of cell division that forms cells with half the number of

chromosomes normally found in cells of the species and is associated with

se$ual reproduction

• In reproduction, an organism produces types of special se$ cells called

gametes, a male gamete and a female gamete

• "hen a male gamete and a female gamete from two di(erent organisms

come together, they fuse in a process called fertilization which results in a

zygote

• This zygote is single celled and undergoes mitosis to eventually form a new

individual

• In humans, cells normally contain KM chromosomes, this is #nown as our

diploid number

• "hen meiosis occurs, this number is halved to 1 chromosomes, our haploid

number

• The number of chromosomes is halves so that when two haploids meet, they

ma#e a diploid cell, the 'rst cell of a new individual

• 8ales produce haploid gametes called sperm, females produce haploidgametes called ova

S;IPPED: 9ERTILISATION: BRINGING GAMETES TOGETHER

SE7UAL REPRODUCTION IN 9LO6ERING PLANTS




• 5lowers are the reproductive organs of angiosperm plants, with di(erent parts

of the +ower serving a di(erent purpose for reproduction

MALE REPRODUCTIVE ORGANS

• The male reproductive organ is called the stamen, which consists of the

anther and the 'lament

• There are usually several stamens in a +ower

• 8eiosis occurs in the anthers and results in the formation of haploid Fhalf a

diploidH pollen grains which in turn has a protective wall and contains two

haploid nuclei

9EMALE REPRODUCTIVE ORGANS

• The female reproductive organ is the pistil, which consists of one or more

carpels which contain and stigma, style, and an ovary

• Inside the ovary is several ovules, this is where meiosis occurs, resulting in

the formation of P haploid cells, one of which is an ovum, or egg

POLLINATION AND 9ERTILISATION

• )ollination is the transfer of pollen from a stamen FmaleH to a mature stigma

FfemaleH. If this occurs, fertilization can ta#e place

• 5ertilisation occurs as/ A germinating pollen grain sends out a tube which

grows down the style towards the ovary The two nuclei of the pollen grain

travel down this tube *ne becomes the tube nucleus, the other divides in

two The pollen tube enters the ovule through the micropyle *ne male

nuclei fuses with the ovum to form a fertilized zygote The other fuses with

two other haploid nuclei to form a triploid

SEL9 POLLINATION AND CROSS POLLINATION

• If pollination involves pollen and stigma from the same plant it is #nown as

self pollination

• ross pollination is when pollen from one plant is transferred to a stigma on

another plant of the same species

• 0elf pollination is an e(ective way for +owers to breed uic#ly and eLciently,

however it gives no rise to variation, meaning that there is a higher li#elihood

of mass death in the case of a disease or environmental change

POLLINATION BY ANIMALS

• 8any Australian +owers are pollinated by insects, birds, and mammals

• 0ome +owers have colours and scents which are appealing to insects such as

bees and wasps so that pollination has a higher rate of occurrence, for

e$ample the colour yellow attracts bees see#ing nectar




END O9 PRELIMINARY COURSE

CHAPTER ?: MAINTAINING A BALANCE

?.1 ACTIVITY AND TEMPERATURE

THE ROLE O9 ENYMES




• All chemical processes occurring within an organism are called its metabolism

• The rate of chemical activity is regulated by enzymes, large proteins

• Enzymes are used over and over again, so cells do not reuire a large

uantity

• They are made in the cell, their manufacture controlled by the nucleus

• i(erent types of cells ma#e di(erent enzymes

9UNCTIONS AND CHARACTERISTICS O9 ENYMES

• Enzymes are biological catalysts, they control the rate of reaction

• Enzymes are speci'c, they a(ect one type of reaction, providing an active

site where it can ta#e place

• Enzymes act on molecules #nown as substrates Feg. atalaseH

• The substrate binds to the active site, causing a temporary change in the

shape of the enzyme, #nown as the induced 't model

• A chemical reaction occurs on the active site and the substrate molecule

splits• The substrate concentration a(ects enzyme activity, Q 0ubstrate R QActivity,

9TID all enzyme active sites are occupied, #nown as the saturation point

• Enzymes reuire speci'c conditions to function most eLciently, temperature

and acidityGal#alinity playing a huge role in how eLcient the enzyme

functions

• Too far from functioning conditions and the enzyme is <denatured=, the active

site warping, and can no longer catalyse reactions

HOMEOSTASIS

• 7omeostasis is the process by which organisms maintain a relatively constantor stable internal environment for body cells

• It consists of/ detecting changes FreceptorH, and counteracting changes

Fe(ectorH

• 7omeostasis is essential for the correct functioning of enzymes

RESPONDING TO CHANGE

DETECTING CHANGES

• Any information that provo#es a bodily response is called a stimulus

•

Environments contain many stimuli and organisms have receptors that detectthem

• Eg. Dight-S)hotoreceptor, 7eat-SThermoreceptor, *$ygen-Shemoreceptor

COUNTERACTING CHANGES

• "hilst receptors ETET changes, organisms too reuire a response to the

change, which is brought by the e(ectors




• Eg of e(ectors R muscles, glands

• To co-ordinate this sensory information, the body uses the nervous system

THE HUMAN NERVOUS SYSTEM

• The nervous system is made up of; the central nervous system, the brain,

and the spinal cord

• This system acts as a control centre which co-ordinates all an organism&s

responses

• It receives information FreceptorsH, and initiates a response Fe(ectorsH

TEMPERATURE AND LI9E

• The temperature of an environment is #nown as the ambient temperature

• To survive, organisms must be able to live within the temperature range of

their environment

ECTOTHERMS AND ENDOTHERMS

• Ectotherm ! An organism which has limited ability to control their body

temperature, their cellular activities generate little heat. Their body

temperature rises with the ambient temperature. Eg. )lants, amphibians, 'sh,

reptiles

• Endotherms ! An organism which maintains their body temperature though

metabolism, independent of the ambient temperature. This ta#es more

energy and so more food is reuired for endotherms. Eg. 8ammals, birds

BEHAVIOURAL ADAPTATIONS TO TEMP CHANGEF

• 8igration ! Animals move to avoid temperature e$tremes

• 7ibernation ! Animals remain in a sheltered spot and lower their metabolism

• 0helter ! Animals see# shelter from e$treme conditions

• 9octurnal Activity ! Animals sleep during day and are active at night

• ontrolling E$posure ! Animals alter their position to e$pose more or less

surface area to sunlight

STRUCTURAL AND PHYSIOLOGICAL ADAPTIONS O9 ENDOTHERMS

• Insulation ! 5ur and feathers, as well as fat #eep organisms warmer in the

colder months, and can be shed in the hotter months to remain cool

• 8etabolic Activity ! Endotherms generate heat as a result of their metabolic

activity. This #eeps the body warm in cold conditions.




• ontrol of @lood 5low ! Endotherms can increase or decrease heat e$change

by controlling blood +ow to the s#in and e$tremities, maintaining a core body

temp

• Evaporation ! @y controlling evaporation of water from their bodies,

endotherms #eep themselves cool. Eg Nangaroos lic# their paws to increase

evaporation therefore increase heat loss

?.5 6ATER 9OR TRANSPORT

THE MAMMALIAN CIRCULATORY SYSTEM

• 8ammals have a closed system, comprising of a pump Fthe heartH, which

sends a +uid Fthe bloodH through a networ# of tubes Fblood vesselsH which

transport it around the body

• @ody +uid drains into the lymphatic system and the lymph vessels return the

+uid to the blood

•

The circulatory system is used for transport of water, gases, and nitrogenouswastes, defence against disease, and to distribute heat around the body

COMPOSITION O9 THE BLOOD

• 8ammalian blood is made up of )lasma, and ellular 8atter

• )lasma ! 8ade up of mostly water, contains some chloride ions and large

plasma proteins. These salts and proteins play a role in maintaining the p7 of

the blood. )lasma also carries urea, carbon dio$ide, products of digestion,

and hormones

• 4ed @lood ells ! ontain the pigment haemoglobin, helping them to perform

their main function/ carrying o$ygen and gases to the cells. In humans, 4@shave no nuclei and remain in the blood for about 1 months before being

destroyed and replaced.

• "hite @lood ells ! About double the size of 4@s, come in two types/

phagocytes and lymphocytes. )hagocytes can move from blood to tissue +uid

and are a vital part of the immune defence, surrounding and destroying any

foreign body that enters the body. Dymphocytes act against foreign material,

creating antibodies.

• )latelets ! Aid in helping the blood to clot

TRANSPORTING SUBSTANCES IN THE BLOOD

0ubstance 5rom To 5orm arried @y*$ygen Dungs @ody

ells

*$yhaemoglobin 4@s

arbon io$ide @ody ells Dungs 8ainly 7ydrogen

arbonate Ions

F@icarbonate

4@s and

)lasma




IonsH

"aste 9itrogenous

8aterial

Diver and @ody

ells

Nidneys 8ostly as rea )lasma

"ater igestive

0ystem and

@ody ells

@ody

ells

"ater 8olecules )lasma

0alts igestive0ystem and

@ody ells

@odyells

Ions in the)lasma

)lasma

THE STRUCTURE O9 BLOOD VESSELS

@lood +ows through a system of tubes or vessels, under the in+uence of the

nervous system which control the +ow and distribution of blood

There are three types of blood vessels/

Arteries ! arries blood from the heart to the cells, thic# walled, elastic, and

muscular. Elastic 'bres allow the vessels to e$pand and recoil with eachheartbeat, maintaining pressure on the blood, sending it in spurts to body

tissues. @y e$panding and contracting, they push blood around the body.

apillaries ! *nly one cell thic#, around C micrometres, so blood cells must

pass through single 'le. apillaries surround tissue cells so no cell is far from

a capillary. 7ave a large surface area to allow e$change of materials between

blood and body cells

eins ! 4eturn blood from the cells to the heart. The walls are thinner and less

muscular than that of arteries, and have a larger diameter. The blood +ows

with much less pressure and so valves, which prevent the bac#+ow of blood,

are present in veins.

The 7eart ! Acts as a pump which #eeps blood circulating in the body.

onsists of the left and right atria FatriumH, and the left and right ventricles.

The atria receive blood from the veins, and the ventricles send blood around

the body through the arteries. The heart aids in the e$change of gas, blood

pic#ing up o$ygen here as it beats around M?-P? times per minute

The )ulmonary ircuit




TRANSPORT MECHANISMS IN

PLANTS

• )lants have two transport systems;

the phloem and the $ylem

• The phloem transports organicmaterials, such as sugars, up and

down the stem to other parts of the

plant

• The $ylem transports water

and mineral ions up from the roots to

the leaves

THE STRUCTURE O9 7YLEM

• The $ylem of +owering plants

consists of $ylem vessels, tracheids, 'bres, and parenchyma

• essels may be up to several metres in length, and as they develop, lignin

Fdead woody cellsH is deposited in their cell walls in a spiral pattern,

strengthening the $ylem vessel and ma#ing it impermeable to water

• "ater enters the plant through the root hairs, travelling across the corte$ into

the $ylem

• "ater can rise in the $ylem at a rate of >2 metres per hour, against gravity

• This rising is brought on by the passive upwards movement brought on by the

pull of the transpiration stream through the stomates.

• "ater is drawn up the $ylem tubes to replace the loss of water throughevaporation

• The branching networ# of $ylem vessels ensures water is transported to all

parts of the plant

• 7owever as the water is pulled upwards some may lea# out into surrounding

tissues or another vessel

• Adhesion-ohesion forces also aid in the water climbing& up the $ylem to the

leaves

THE STRUCTURE O9 PHLOEM

• The phloem of +owering plants contains phloem 'bres, phloem parenchyma,sieve cells, and companion cells

• 0ieve cells are elongated cells which form a series of connecting tubes

• 0ieve cells aid in the transport of carbohydrates from the phloem to the plant

• ompanion cells are lin#ed to the sieve cells and ta#e on many metabolic

functions for the sieve element




• *rganic materials, including sugars, amino acids, and hormones are

transported by the phloem in a movement #nown as translocation

• Translocation enables a plant to distribute resources wherever needed in the

plant

• <0ource-to-sin#= or the <)ressure 5low= depositing of materials created by

photosynthesis into the roots• Amino acids and mineral nutrients are loaded into the phloem at the source

of photo synthesis, the leaves

• These materials then +ow towards a <sin#=, the region on a plant where

sugars and nutrients are being actively removed from the phloem, eg. The

roots, stems, and +owers

• The materials are then used in metabolism or stored in the plant, glucose as

starch

?.< REGULATION O9 SUBSTANCES

6ATER IN CELLS

• "ater is a solvent for all metabolic reactions and is the transport medium for

distributing substances in the body

THE REMOVAL O9 6ASTES

• As a result of all the metabolic functions occurring in the body, wastes are

created

• If these wastes were allowed to accumulate in cells, it would slow down

metabolism and poison the cells, therefore these wastes need to be removed

uic#ly

• i(erent animals e$crete di(erent waste products

THE ROLE O9 THE ;IDNEY

• The primary role of the #idney is to regulate salt and water concentrations in

the body, and e$crete nitrogenous wastes

• 8ammals e$crete the nitrogenous waste urea

• 5ish e$crete ammonia, coupled with much larger amounts of water Fin

freshwater 'shH

THE 9ISH ;IDNEY

• The primary role of the #idney is the regulation of water and salt

concentrations in the body

• In 'sh, e$cretion of nitrogenous wastes, such as ammonia, occurs across the

gills




• The #idneys ad%ust the levels of water and mineral ions in the 'sh&s body in

order to maintain a constant concentration of internal +uid

9RESH6ATER 9ISH

• 5reshwater 'sh maintain a higher concentration of solutes in their body than

in their surroundings

• Therefore, water tends to continually di(use into the 'sh&s body, which it

must then get rid of

• Their #idneys produces large amounts of e$tremely diluted urine in an almost

continuous stream to do this

• As fresh water has a lower concentration of ions than the 'sh do, the #idneys

actively reabsorb salts to prevent loss

SALT6ATER 9ISH

• 0alt water 'sh have the opposite problem to freshwater/ their internal body

+uids are less concentrated than the surrounding water

• To avoid water loss, marine 'sh continually drin# salt water, absorbing both

the water and the salts

• The water is retained and the salts are e$creted via the gills and #idneys

• ue to this lac# of water availability, salt water 'sh e$crete much less urine

that freshwater, and is much more concentrated to minimise water loss

RENAL DIALYSIS

• 4enal dialysis is the arti'cial process in which wastes in the blood are

removed by di(usion across a semi-permeable membrane

• ialysis helps those whose #idney function is so impaired that products of

metabolism, such as urea, are built up in the body instead of e$creted

• If both #idneys stop wor#ing due to disease, the patient&s life is immediately

threatened, ma#ing renal dialysis e$tremely important.

•




THE MAMMALIAN ;IDNEYS

• The Nidneys are compacts and bean shaped

• They produce urine, which contains nitrogenous materials from the cells

• rine leaves the #idneys from the ureters and is stored in the bladder until

being e$creted• 8ammals have two #idneys

• Each is made up of around a million small 'ltering units called nephrons

•

•

• The #idneys continuously process an enormous volume of blood to form a

small volume of urine

• There are three processes in the formation of urine/ 'ltration, reabsorption,

and secretion

• 9i*(#io$ ! @lood is brought to the #idneys by the renal artery, which divides

into smaller vessels which after reaching the @owman&s apsule, form a

networ# of capillaries called the glomerulus. 5rom the glomerulus, plasma

and small soluble molecules pass into the @owman&s apsule through passive

'ltration, and the 'ltrate contains some substances which may be reabsorbed

and used by the body, and some wastes. As the substances are moved along


iagram of a

9ephron

iagram of a Nidney



the nephron tubule, its composition is ad%usted until it only contains wastes,

after which it is e$creted as urine.

• 5iltrate passing into the @owman&s apsule may include/ water, nitrogenous

wastes, food materials, bicarbonate ions, hormones, and ingested substances

such as penicillin

•R%#so('io$ ! 0urrounding each nephron is a large capillary networ#. Asthe 'ltrate travels down the tubule, materials that can be reused are

reabsorbed into the blood, such as glucose, amino acids, and water. It is an

active process which reuires energy and ta#es place most notably in the

loop of 7enle

• S%c(%io$ ! A selective process by which the body transports substances

from the blood to the nephron

REGULATION O9 BODY 9LUID COMPOSITION

• The nephron is a regulatory unit, it reabsorbs materials reuired to maintain

homeostasis• This regulation helps to maintain the constant composition of the blood and

intestinal +uid

• In the pro$imal tubule, bicarbonate ions F*H are reabsorbed and there may

be some secretion of hydrogen ions, this is done to maintain a constant blood

p7 level

• The loop of 7enle is involved in the 'ltration and reabsorption of water

ACTIVE AND PASSIVE TRANSPORT

• *smosis and di(usion are passive forms of transport across cell membranes,

that is they don&t reuire energy• In the #idneys, both active and passive transport is used

• )assive transport occurs in 'ltration and osmosis of water bac# into blood

• Active transport occurs in secretion of substances into the nephron, transport

of nutrients bac# into the blood, and selective reabsorption of salts

THE ENDOCRINE SYSTEM AND HORMONES

• The endocrine system consists of ductless glands which secrete hormones;

chemical messengers that travel in blood

• 7ormones bring about change in the metabolic activity of the body and are

#ept at a fairly constant level by feedbac# systems

4ole escriptionontrol of the Internal

Environment

7ormones maintain homeostasis by regulating the

amounts and type of many body chemicalsEmergencies 7ormones enable the body to cope with stress !

physical or emotionalrowth 7ormones ensure growth and development ta#e place




in a smooth, controlled way4eproduction 7ormones are involved in reproduction from gamete

formation to maintenance of the placenta, birth and

nourishment of the newborn

HORMONAL REGULATION O9 6ATER AND SALT LEVELS

• Two hormones; antidiuretic hormone FA7H and aldosterone, help to regulate

salt and water concentrations, as well as blood pressure and volume

• The blood that leaves the #idney via the renal vein has had its nitrogenous

wastes removed and its water and salt composition balanced

• The function of the #idney is twofold/ it acts as an e$cretory organ, and has a

homeostatic function, helping to maintain a constant internal composition of

body +uids

ANTIDIURETIC HORMONE ADHF

• 4eabsorption of water is controlled by A7

• A7 is made by the hypothalamus but is stored in the pituitary gland

• 4eceptors in the hypothalamus monitor the concentration of the blood/ if

there is a loss of water, A7 is released into the blood and circulates to the

#idneys

• A7 increases the permeability of the walls of the distal tubules, allowing

water to pass freely out of the tubules bac# into the body

• As the blood returns to normal concentration by negative feedbac#, less A7

is secreted

• If blood concentration is low, after a lot of water has been drun#, less A7 is

released and the permeability of the distal tubules is decreased, allowing

more water to be passed as urine

ALDOSTERONE

• Aldosterone regulates the amount of salt in the body

• It is produced in the adrenal glands, situated above the #idneys

• If there is an increased blood volume and blood pressure, resulting from high

salt concentrations, to output of aldosterone is reduced

• Dess salt and water is reabsorbed by the nephron tubules and increased

amounts of salt and water are lost in the urine

• If the body needs salt, water is not retained, the adrenals release more

aldosterone, and salt is reabsorbed from the tubule

ENANTIOSTASIS: SURVIVAL IN AN ESTUARY

6HY IS AN ESTUARY SPECIAL




• An estuary forms where a river meets the sea, fresh water draining from the

land mi$es with saline water from the sea

• Estuaries are rich, productive ecosystems which act as nutrient traps

• The sediment traps provide a rich soup& that supports a vast community of

organisms

• The water is calmer and more shallow than the sea and there is plenty of lightfor photosynthesis

• Estuaries are used by many species of 'sh as uiet breeding and nursery

places for their young

• 7owever there is a salinity gradient in an estuary, the salinity +uctuating

greatly as the tide goes in and out

• Enantiostasis is the maintenance of metabolic and physiological functions in

response to variations in the environment, and it is this process which helps

organisms survive in this environment of +uctuating salinity

• 7owever it is not alone, behavioural adaptions playing a role in survival in

estuaries

• 5ast swimming animals can move away, molluscs can close their shells,

bottom dwellers can burrow deep into the mud or sand

MAINTAINTING SALT CONCENTRATIONS IN PLANTS

• )lants, unli#e animals, cannot move away from the +uctuating conditions in

an estuary, and so must 'nd ways to cope with a high salt environment !

these plants are #nown as halophytes

• Three mechanisms which enable halophytes to control their salt levels are;

salt e$clusion, salt e$cretion, and salt accumulation

• 0alt e$cluders prevent entry of salt into their roots through 'ltration, a

passive process

• 0alt e$creters have special glands, usually in the leaves, where salt is

concentrated and actively secreted, which is then washed o( by rain

• 0alt accumulators concentrate salt in a part of the plant, usually bar# or old

leaves, and then drop that part of the plant o(, losing the salt

MINIMISING 6ATER LOSS IN PLANTS

• 6erophytes are plants adapted to dry conditions, there adaptions include/

S("c"(#*

• Deaves with a thic#, wa$y cuticle to reduce water lost by evaporation

• 4educed leaf surface area

• 4e+ective leaf surfaces

• 7airy leaves, which reduce air+ow across the leaf to reduce evaporation

• 0un#en stomates or a reduced amount of stomates

• 4olled up leaves to minimise water loss




P!sio*o-ic#*

• ertically hanging leaves that change position with the sun to reduce heat

absorption and water loss

• The closure of stomates during the hottest part of the day

•

ormancy period where all above-ground parts die o( • Tough, hard seeds that can survive long dry periods

• Tolerance to drying out

CHAPTER : BLUEPRINT O9 LI9E

.1 THE EVIDENCE 9OR EVOLUTION

ENVIRONMENTAL CHANGE

• Evolution is the change in living organisms over many generations

• Evolution can be caused by changes in an organism&s environment, such as

temperature changes or changes in water salinity, or by competition fromother organisms, such as competition for 'nding food and water

EVIDENCE 9OR EVOLUTION

PALAEONTOLOGY

• )alaeontology is the study of fossils, and can provide evidence for how

organisms have changed over time

• Transitional forms are e$amples of organisms that indicate the development

of one group of organisms from another or from a common ancestor, which

can be seen in the fossil record

BIOGEOGRAPHY

• @iogeography is the study of the distribution of living things/ where certain

animals and plants are found in the world

• 5or e$ample, the animals and plants found in Australia are vastly di(erent to

those found in Asia

• @y loo#ing at the pattern of distribution of an organism today, plus its fossil

distribution in the past, we are able to reconstruct its evolutionary history

COMPARATIVE EMBRYOLOGY

• omparative embryology is the study of embryos of di(erent organisms,

loo#ing for di(erences and similarities between them

• A similarity between embryos suggests that the organisms came from a

common ancestor

COMPARATIVE ANATOMY




• omparative anatomy is the study of the di(erences and similarities in

structure between di(erent organisms

• The structures which the organisms have in common are evidence of similar

inherited characteristics from common ancestors

• An e$ample of this is the )entadactyl Dimb, a similar basic pattern in the

bones of arms and legs shared by most land vertebrates

BIOCHEMISTRY

• @iochemistry is the study of similar molecules between di(erent organisms,

which suggests genetic closeness

• 8olecules such as haemoglobin, 49A, and hormones are studied

• "hen studying proteins, amino acid seuences are compared, and if similar,

are a clue to genetic relationships eg. 7umans and himps

• 0tudy of blood and its compatibility when mi$ed is also used within

biochemistry, with closely related organisms displaying a small antigen-

antibody reaction when e$posed to foreign blood• Today these lin#s can be studied directly using 9A seuencing to compare

the bases and 'nd similarities

DNA HYBRIDISATION

• 9A hybridisation can be used to identify similarities in 9A structure

• 0pecies which show a high degree of hybridisation are e$pected to have

diverged recently from a common ancestor as the seuences will be very

similar• The process has K steps/

>. Two strands of 9A are separated by heat. The single strands formed are mi$ed with single strands from another

species1. The two di(erent strands will %oin to form a hybrid molecule, however not

all bases will match due to di(erencesK. The degree of pairing depends on this similarity between seuences, if it

'ts well there is a high degree of pairing, and so the organisms show close

relation

OTHER EVIDENCE 9OR EVOLUTION

THE AGE O9 THE EARTH

• 0cientists believe life on Earth has e$isted for over 12?? million years

• uring this time, continents have changed places and environmental

conditions have changed

• @y dividing this time into geological eras and periods the evolution of living

organisms can be traced




DOMESTICATED ANIMALS AND CULTIVATED PLANTS

• 7umans have been successful in breeding specialised animals and plants,

selecting the variations they prefer, demonstrating how evolution could have

occurred

EVOLUTION BY NATURAL SELECTION

>. In any population, there are variations between individuals. In any generation, there are o(spring that do not reach maturity and

reproduce; the characteristics of these organisms are removed from the

population1. Those organisms that survive and reproduce are well adapted to that

environment, they have favourable variationsK. These favourable variations are then passed on to o(spring and become

more common in the population

CONVERGENT EVOLUTION

• onvergent evolution occurs when natural selection over many generations

results in similar adaptions in species which live in similar environments

• 5or e$ample, seals and dolphins have much the same adaptions F+ippers,

strong swimmers, can hold their breath etc.H yet belonging to di(erent orders

of mammals

• espite being vastly di(erent animals, they e$hibit similar variations

DIVERGENT EVOLUTION

•

ivergent evolution Falso #nown as adaptive radiationH is the process thebegins with one species Fcommon ancestorH and produces organisms that

loo# di(erent from each other because they have evolved from isolated

populations in di(erent environments

• The most famous e$ample of divergent evolution is harles arwin&s

alapagos 5inches, >K species of 'nches displaying di(erent variations, but

who evolved from a common ancestor

.5 MENDEL AND THE INHERITANCE O9 CHARACTERISTICS

VARIATION: ENVIRONMENT OR INHERITANCE

There are two causes of variations in populations Fand by e$tension,

evolutionH/ Environment and inheritance

Environmental variation occurs because of the conditions that an organism

e$periences during its lifetime, for e$ample an animal may be small because

it has been unable to 'nd food

Environmental variation can change during an organisms lifetime

Inheritance however, is '$ed for the life of the organism




Each trait has a speci'c gene and each individual possesses a uniue

combination of these genes

MENDELS E7PERIMENTS

The 'rst studies of inheritance were carried out by regor 8endel in the

>P??s using the garden pea

7e published his 'ndings in >PMM, however is was totally ignored, and the

signi'cance of his wor# was not fully realised until the beginning of the ?th

entury

6HY DID MENDEL SUCCEED

8endel was very luc#y in the sense that the pea plant is a perfect sub%ect for

the C tests he undertoo#

7e studied seven di(erent characteristics in pea plants/ seed shape, seed

colour, pod shape, pod colour, +ower colour, height, and type of +owers

@efore testing, he pure-bred his plants, ma#ing sure the characteristic was

consistent

7e then deliberately and carefully crossed one variety with another,

pollinating by hand and removing stamens to eliminate self-pollination

7e repeated this process many times, #ept careful records, and used

mathematics to improve and record his studies and 'ndings

MENDELS E7PLANATIONS

DOMINANT AND RECESSIVE GENES

"hilst most people in 8endel&s time believed that inheritance occurred by<blending= FTall 0hort R 8ediumH, 8edel determined that there were two

forms/ dominant and recessive

Even though 8endel had no #nowledge of chromosomes, he came to the

conclusion that the units of inheritance which control a characteristic must

come in pairs, one received from each parent and combine at fertilisation

8endel called these units <inheritance factors=, but today we call them genes

Each individual has a pair of genes for each characteristic

The members of the gene pair are called alleles

"hen we refer to all the genes of an organism, we tal# about its genotype

"hen we refer to the appearance of an organism, we tal# about itsphenotype

*rganisms with identical genes in their pair Feg. TT, or ttH are called

homozygous

*rganisms with di(erent genes in their pair Feg, TtH are called heterozygous

MENDELS LA6S




• 8endel summarised his wor# to e$plain the inheritance of characteristics in

two laws

• The 'rst law, The Daw of 0egregation, states that factors for the same

characteristic occur in pairs in an individual. These pairs separate at gamete

formation, so that a gamete contains only one of each factor

.< CHROMOSOME STRUCTURE = THE ;EY TO INHERITANCE

THE IMPORTANCE O9 CHROMOSOMES

In >B?, it was suggested that 8endel&s inheritance factors, genes, are

carried on chromosomes ! The hromosomal Theory of Inheritance

• It was noted that/

>. uring meiosis, the chromosomes in each cell lined up in pairs, and each

pair of chromosomes was the same size and shape

. 7omologous pairs of chromosomes segregate during meiosis so that each

gamete receives on chromosome from each pair1. After fertilisation, the resulting zygote had a full set of homologous

chromosomes

THE CHEMISTRY O9 CHROMOSOMES AND GENES

THE STRUCTURE O9 DNA

• Each chromosome is made up of about M?3 protein

and K?3 9A Feo$yribonucleic AcidH

• 9A is double-stranded and is made up of a series

of subunits called nucleotides

• *ne nucleotide contains a sugar, a phosphate, and

a base

• The sugar is #nown as deo$yribose




There are K di(erent bases in 9A - Adenine FAH, uanine FH, Thymine FTH

F*r racil FH in 49AH, and ytosine FH

In 9A the bases of each side are %oined together, A can only pair with T, and

can only pair with

If the 9A molecule did not have a twist, it would resemble a ladder, the

sides being the sugar phosphate groups, and the bases being the steps

Information is stored on the seuencing of bases along the 9A molecule,

and a gene is a particular set of bases

i(erent genes have di(erent seuences and are of di(erent lengths along a

chromosome

9ORMATION O9 GAMETES

• In meiosis, haploid gametes are formed, which contain half the normal

FdiploidH number of chromosomes as the chromosome pair separate• uring meiosis, chromosome material is e$changed between chromosomes in

a process called crossing over

• This results in the production of completely uniue gametes

VARIATION AS A RESULT O9 SE7UAL REPRODUCTION

• All gametes vary genetically due to meiosis

• In se$ual reproduction, two gametes are brought together and in fertilisation,

fuse to form a uniue diploid zygote

• This increases variation within a species because it is sheer chance that

determines which gametes will be involved, and the chance that the sametype of sperm and egg being produced and uniting is almost zero

VARIATIONS O9 MENDELS RATIOS

• 0ome characteristics do not display simple dominanceGrecessivness, this is

#nown as co-dominance or incomplete dominance

• These characteristics have two alleles which are @*T7 e$pressed whenever

present

• This means that there are three possible genotypes and three possible

phenotypes

• An e$ample are snapdragons, which have red and white alleles FTheir

possibilities are/ "hite "", 4ed 44, or )in# 4"H

• The phenotype of a co-dominant, heterozygous organism is a blend of the

two co-dominant alleles, Feg. Tall 0hort R 8ediumH

• The ratios of o(spring crosses therefore do 9*T conform with 8endel&s ratios




SE7 LIN;AGE

• 0e$ FgenderH is a genetically determined characteristic

• 7umans have KM chromosomes, two of which, are se$ chromosomes

• In females, both are 6 chromosomes F66H, in males, there is one 6 and one :

chromosome F6:H• 8ales receive their 6 chromosome from their mother, and their :

chromosome from their father, which can carry very few genes

• 6 chromosomes carry a wide variety of genes and it is the genes on the 6

chromosome only which e(ect characteristics FphenotypeH

• "ith this in mind, males therefore are much more li#ely to e$press a

recessive trait as they only have one 6 chromosome on which the

characteristic can be e$pressed

ENVIRONMENTAL E99ECTS

•

The environment includes all the surrounding forces which act on anorganism or its cells

• The e$pression of a gene, as well of the phenotype of an individual, can be

a(ected by the environment

• This can be shown in twins, as although they are genetically identical, due to

growing up in di(erent environments, they are not identical organisms

• Environmental factors can include nutrition, health, and the physical

environment around the organism

.> THE MECHANISM O9 INHERITANCE

DNA REPLICATION

• A replica is a copy of something, and during mitosis chromosomes are

replicated

• 9A replication begins with the separation of its two strands, the bonds

holding them together brea#ing and the strands <unzip=

• @inding proteins prevent the strands from re-attaching as a complimentary

copy of each strand is constructed from new sugar-phosphate-base units

DNA AND THE PRODUCTION O9 POLYPEPTIDES

• 9A is the genetic, or inheritable, material in cells

• It can be replicated and the information it carries can be passed on to new

cells

• This genetic information is organised into units #nown as genes, certain

seuences of bases along a 9A strand

• Each gene contains coded information reuired to ma#e polypeptides

• "hilst 9A does not directly ma#e proteins for the cell, through transcription

and translation it provides the information for the cell to synthesise them




THE GENETIC CODE

• To manufacture a protein, information is reuired about the number, type,

and seuence of amino acids that ma#e up a protein molecule

• This information can be found in a code on the 9A strand

•

The genetic code therefore, is the seuence of bases along the 9A strand• A set of three bases is #nown as a codon and this codon is the code for one

amino acid

• There are in total M> codons which specify one of the ? amino acids

PROTEIN SYNTHESIS

• )roduction of a protein involves/

>. 9A ! A gene on the 9A strand provides the information reuired to ma#e

the polypeptide. 8essenger 49A Fm49AH ! arries information from the 9A Fin the nucleusH

to the ribosomes in the cytoplasm Fas 9A cannot e$it the nucleusH1. Transfer 49A Ft49AH ! @rings amino acids to the ribosomes so they may be

able to be lin#ed together to build the polypeptide chain. Each t49A contains

an anti-codon which contains complementary bases to those found on the

m49AK. 4ibosomes ! Acts as a site for polypeptide synthesis in the cytoplasm as the

lin#ing of amino acids into a polypeptide

chain occurs2. Enzymes ! Involved in catalysing the

reactions

STAGES O9 PROTEIN SYNTHESIS

TRANSCRIPTION

• The double 9A strand in the nucleus unwinds to form two strands with

revealed bases• 49A then moves along one strand, lin#ing complementary 49A nucleotides

together to form a m49A strand F9@. There is a speci'c codon for the

beginning and end of the strandH

• After the entire gene is copied, the m49A moves from the nucleus to the

cytoplasm

ACTIVATION O9 AMINO ACIDS




• In the cytoplasm, an enzyme attaches amino acids to speci'c t49A molecules

TRANSLATION

• The m49A strand binds to a ribosome in the cytoplasm at the end of the

strand which e$presses the <0tart= codon FAH

• A t49A codon on the t49A strand carrying amino acids also binds to the

<0tart= codon within the ribosome

• The ne$t codon on the t49A strand is bound to the ne$t on the m49A strand

and the amino acid is holds is bound, via peptide bond, to the 'rst amino acid

• The 'rst t49A codon is then released from the ribosome, and the ribosome

continues along each strand, continuing this process to form a polypeptide

chain Fa chain of bounded amino acidsH

• *nce the <0top= codon on the m49A is reached, the polypeptide chain is

released into the cytoplasm

• The chain then undergoes speci'c twisting, folding, and shape changing to

eventually form a protein

MUTATIONS

• ariation arises in se$ually reproducing organisms by the recombination and

crossing over of chromosomes in meiosis, and the fusion of two haploid sets

of chromosomes in fertilisation

• 8utation is an alternative to this, which can lead to new alleles in an

organism as changed occur in the 9A on a chromosome




• 8utation however, is often lethal, causing the mutated cells to die

• It is only when the mutated form survives that it can increase the variation of

a population

RADIATION

• uring the ?th entury, #nowledge of the mutagenic nature of radiation Feg.

, nuclearH became much more abundant

UV RADIATION

• ltraviolet radiation from sunlight is common mutagen, which can result in

the bases in a 9A strand to be lost, or cause Thymine bases in the same

strand o lin# together, ultimately preventing 9A replication from occurring

normally

• radiation is also #nown to be a ma%or cause of s#in cancers, and due tothe increasing depletion of the ozone layer, the rate of mutations is li#ely

to rise

IONISING RADIATION

• 4adiation from radioactive materials and $-rays is mutagenic

• These radiations can brea# 9A strands of even whole chromosomes,

resulting in mutation or cell death, depending on the amount of damage

• 0urvivors of ionic radiation, such as those from the 7iroshima bombings and

the hernobyl disaster still e$hibit signs of the radiation&s e(ect today

• The victims have been shown to su(er immediate damage to the 9A in theircells, as well as damage which fully surfaced years later

BEADLE AND TATUM = ONE GENE: ONE POLYPEPTIDE

In >BK>, @eadle and Tatum published results from an e$periment which

involved the radiation of bread mould to inhibit a gene

The results recorded provided evidence of a lin# between genes and proteins

Fwhich are built from polypeptidesH

They used $-rays to cause mutations in millions of strains of the mould which

caused the strain to lac# the ability to produce one of the essential nutrients

for normal growth They determined that this inability was caused by the absence of a necessary

enzyme

@y growing di(erent strains with di(erent combinations of nutrients, they

were able to establish which enzyme was lac#ing in each mutant strain, and

determined that each genetic mutation was at a speci'c site on the mould&s

chromosomes




They concluded that di(erent sites on the chromosomes were associated with

a certain enzyme, leading to the <*ne gene, one polypeptide= hypothesis

DAR6IN REVISITED

• arwin&s theory of evolution by natural selection can be e$plained and

e$panded upon by the genetic information we now have, as we now #now

that variation stems from/>. The random fusion of gametes in se$ual reproduction. rossing over of homologous chromosomes during meiosis1. 4andom assortment of chromosome pairs in meiosisK. 8utations of chromosomes and genes

• enetic variation is e$pressed in the phenotype of an organism

• 0ome phenotypes, the more favorable ones, will survive and reproduce better

than the others

• *ver time, natural selection will operate to change the proportions of certain

genes in a population

NATURAL SELECTION VERSES PUNCTUATED EQUILIBRIUM

• arwin&s theory of 9atural 0election proposes that populations change

gradually over time

• To support this theory, we should see a long seuence of gradual changes to

an organism&s anatomy in the fossil record ! this is usually not the case

• This has been e$plained by supporters of the theory of 9atural 0election by

the rare nature of fossilization occurring, coupled with the rare nature of

'nding a fossilized organism

• @ecause of this rare nature, it seems as though new species suddenly appear,

show little change throughout their life, and then become e$tinct

• It Is the theory of )unctuated Euilibrium that proposes that rather than a

gradual change in an organism, as arwin suggests. Evolution occurs rapidly,

followed by a long period of stability, or euilibrium

.? REPRODUCTIVE TECHNOLOGIES AND GENETIC ENGINEERING

MANIPULATING THE GENE POOL

Ever since humans began taming animals and farming crops they have been

controlling the breeding of the organisms in their care

@y doing this, humans have been able to improve the characteristics of these

organisms for human use and purposes Feg. Darger cattle, faster growing

cropsH

0elective @reeding means deliberately crossing individuals of the same

species with desired characteristics, causing the o(spring to also possess

these characteristics




*ver generations, the preferred characteristics will become the ma%ority due

to the changes that have been made to the genetic composition of a

population

This can be seen as a controlled version of arwin&s Theory of 9atural

0election

ARTI9ICIAL INSEMINATION AND POLLINATION

• Arti'cial insemination is the in%ection of male semen into a female, and is

used commonly by animal breeders for larger animals such as cows, sheep,

and horses

• enerally, the sperm collected is from a male with favourable characteristics

• *nce collected, the sperm can then be transported and used to inseminate

females over a much wider area than by normal mating

• )lants can be arti'cially pollinated by brushing fertile stigmas with pollen

from plants, again with desired characteristics

• These techniues lead to uic#, widespread genetic changes within a speciespopulation

CLONING

• loning is the process of producing genetically identical organisms

• loning occurs naturally in ase$ual reproduction, a clone being is collection of

genetically identical copies

• The cloning of plants has been used for many years, however only recently

have scientists been able to clone a domestic animal, a sheep, olly, being

successfully cloned in >BBC by a techniue #nown as nuclear transfer

technology• uring her life, olly was able to give birth to K healthy lambs, indicating

correct functioning of the cloned cells and genes

• 0ince >BBC, scientists have been able to, albeit with low success rates, clone

such animals as mice, goats, pigs, cattle, and horses

GENETIC ENGINEERING

@iotechnology is the use of various techniues to change organisms at a

molecular level

This permanently alters the genetic blueprint of an organism, as desirable

genes from one organism are isolated, and then inserted into anotherorganism

PRODUCTION O9 A TRANSGENIC SPECIES

• enetically modi'ed organisms are those which have had their genetic

ma#eup deliberately modi'ed by either selective breeding, mutation, or

genetic engineering




• A transgenic species is one which contains a new piece of 9A spliced into a

chromosome in each of its cells

• This new piece of 9A usually allows the organism to produce a protein which

it would otherwise be unable to produce

• The inserted 9A may come from either an entirely di(erent species, or a

di(erent organism within the same species• The production of a transgenic species involves several steps

>. A useful gene and the chromosome it is on is identi'ed. The gene is isolated, or cut-out& of the 9A strand1. In some instances, multiple copies of the gene may be made

Fthrough insertion into uic#ly-reproducing bacteriaHK. The gene is inserted into the cell of another organism, sometimes

with the aid of a vector. The method of insertion is reliant on the

cell

• *nce the gene is inserted, it needs to become part of the genetic material of

that organism, and must be able to be e$pressed

• The organism is not counted as a transgenic organism unless it is able topass on this trait to its o(spring

• Transgenic species have been developed to improve agricultural crops, such

as pest-resistant wheat and cotton

• Divestoc# has also been modi'ed to be resistant to disease or to improve

their meat uality

ETHICS AND TRANSGENIC SPECIES

• 8any social, economic, and ethical issues arise from genetic modi'cation,

especially regarding areas such as/

• 5ood safety and health, environmental protection, regulating issues, socialand economic e(ects, and ethical and moral issues

POTENTIAL IMPACTS ON GENETIC DIVERSITY

• An issue that stems from the use of reproductive technologies is the loss of

genetic diversity which it poses

• If more genetically modi'ed plants and livestoc# are used, local varieties will

lose value on a global scale

• Dess diversity also results in less resilience in a species, following on from

arwin&s ideas of natural selection ! if a change in the environment occurs,

all of the species will su(er due to being genetically identical

E7AMPLE: BT COTTON

• @ascillus thuringiensis is a bacterium that naturally produced chemicals

which #ill insects

• It is used e$tensively in transgenic crops, allowing the crops to defend

themselves against insect predators




• 7owever, if these @t crops become standard throughout the world, other

varieties will be lost, and the crop itself will become more vulnerable due to a

lac# of diversity if the environmental conditions change

• Although these reproductive technologies can be e$tremely bene'cial for the

health and prosperity of crops and livestoc#, we must ta#e into account the

negative conseuences, that is a much thinner range of genetic diversity,which will result from widespread use of these technologies

CHAPTER : THE SEARCH 9OR BETTER HEALTH

.1 6HAT IS A HEALTHY ORGANISM

DE9INING HEALTH AND DISEASE

• e'ning health& is not easy as it has many components, some sub%ective

• e'ning disease& has a similar problem, as it is sub%ective, depending on an

individual&s normal level of functioning

• The "7*&s de'nition of health is/ <a state of complete physical, mental and

social well-being and not merely the absence of disease or in'rmity=

THE MAINTENANCE O9 HEALTH

MITOSIS AND GENES

• The maintenance of health of an organism is assisted by the maintenance

and repair of the body&s cells and tissues

• The function of genes is to ensure all cellular processes are able to continue

• 8itosis allows organisms to grow and to produce genetically identical, correct

cells for repair• ell i(erentiation ! the process by which a less specialised cell becomes

more specialised

• hanges or mutations in the genetic material may occur during the life of an

organism, which can be damaging to healthy cells

• 7ealthy cells have their cell cycle carefully regulated, brought on by the

proteins produced by di(erent types of genes

• "hen tumour suppressor genes mutate, they lose their ability to control cell

division

• The rate of cell division increases and causes a tumour

• i(erent types of cells become specialised for di(erent functions within a

multicellular organism ! ell 0pecialisation

.5 THE IMPORTANCE O9 CLEANLINESS

IN9ECTIOUS AND NON4IN9ECTOUS DISEASE

• isease may come from the organism itself, or from an outside source, such

as another organism or environmental factors




• iseases can be classi'ed as infectious Fable to be caught&H or non-infectious

• Infectious diseases are caused by a pathogen, an infecting organism

• A non-infectious disease is caused by hereditary, lifestyle, or environmental

factors

• )athogens can be/ prions, viruses, bacteria, protozoans, or fungi Fe$plained

further onH

CONTRIBUTING 9ACTORS

• Three interacting factors contribute to health and disease/ the host organism,

the agent of disease, the environment

• The 7ost ! *rganism resistance to infection varies, individuals vary, and the

resistance of a particular individual can vary over time. A healthy person

might resist an infection which is devastating to another, people under stress

may succumb more easily to infections, a person&s resistance may be

stronger than another&s, and a person&s lifestyle may di(er to another&s

• The Agent ! 8ost infective agents only a(ect one species, for e$ample catin+uenza is not passed to humans. The dose of infection may also be too

small to have a signi'cant e(ect, or the e(ect on the host may be varied due

to the body&s reaction to the pathogen

• Environment ! The nature of the environment will a(ect the li#elihood of a

pathogen growing and being passed from on host to another. 8any infectious

agents are spread in crowded, unhygienic conditions

CLEANLINESS AND CONTAMINATION

• eneral hygiene and cleanliness are important in reducing the transmission

of infectious diseases• This can include personal hygiene such as hand washing, or societal hygiene

such as sewage and handling of food

• The provision of clean water and disposal of waste water or sewage is a

public health issue, water supplied to houses must be safe to drin#

PATHOGENS

• "hen an organism causes disease, they are called a pathogen

• To cause disease, organisms reuire the right conditions to multiply and be

transmitted

HO6 DISEASES ARE SPREAD

• Airborne ! ust and droplets in the air may carry microorganisms

• ontact ! ontagious or infectious diseases can be caught by direct or

indirect contact

• @y other *rganisms ! *rganisms #nown as vectors may transmit diseases,

eg. 8osuito




.< THE SEARCH 9OR MICROBES AS CAUSES O9 DISEASE

PLAGUES AND EPIDEMICS

MICROBES AS THE CAUSE O9 IN9ECTIOUS DISEASE

• ntil the mid->Bth entury, people thought that living things came intoe$istence from non-living matter, spontaneous generation

• Two scientists who contributed most to the understanding of causes of

diseases were Douis )asteur, and 4obert Noch

LOUIS PASTEUR

• iscovered that most infectious diseases are caused by microorganisms, or

germs

• This became #nown as the germ theory of disease

• 7is demonstration, via the swan-nec#ed +as# e$periment, proved that living

micro-organisms are present in the air, destroying the theory of spontaneousgeneration

• 7e also discovered the techniue of )asteurisation, heating a liuid to 22 to

destroy any microbes present

• 7e also demonstrated the 'rst idea of vaccination, infecting 2 sheep with a

small dose of @acillus anthracis, and then 2? sheep, including the original 2

with a large dose

• Those who were administered the small dose and then the large dose

survived, whilst those administered only the large dose died

ROBERT ;OCH

• 0ucceeded in isolating the bacterium which causes the disease from the

blood of dying animals

• 7e found that healthy animals in%ected with the blood of diseased animals

became diseased

• To prove that a bacterium cause a certain disease, he isolated it and in%ected

an animal with only the isolated bacterium

• Noch&s )ostulates describe the criteria which must be met if we are to be sure

a particular micro-organism causes a disease

MALARIA

• aused by the protozoan parasites of the genus )lasmodium, transmitted by

the female Anopheles mosuito

• 5irst identi'ed by 4onald 4oss

• espite many programs to eradicate it, malaria remains a ma%or health

problem in tropical and sub-tropical areas

AGENTS O9 DISEASE




• An infectious disease is one that is caused by a pathogen and can be passed

on from one organism to another. These pathogens include/

PRIONS

• Infectious agents that cause brain disease in mammals

• They are proteins that have been altered to an abnormal shape

• iseases caused by prions include 8ad ow isease in cattle, and

reutzfeldt-Ua#ob disease in humans

VIRUSES

• ery small, only visible with an electron microscope

• 9o cellular, simply nuclear material F9A or 49AH encased in a protein coat

• iruses in%ect their 9A into another cell and this in%ected cell produces new

viruses which escape to infect others

• There are no cures for viruses, only prevention through vaccination

• iruses include smallpo$, measles, in+uenza, and AI0

BACTERIA

• )rocaryotic cells ! lac#ing of a nucleus or membrane

• @acterial diseases can be treated by antibiotics

• E$amples include tetanus, chlamydia, and Uohne&s disease

PROTOOANS

• 0ingle celled, eu#aryotic Fcells encased in a membraneH organisms

9UNGI

• Eucaryotic organisms, mostly comprised of microscopic tubular 'laments

• E$amples of diseases cause by fungi is tinea or athlete&s foot, and ringworm

MACROPARASITES

• Darge parasites that can be seen with the na#ed eye

• Eg. Dice, mites, tic#s, and +eas in animals and mites and aphids in plants

THE ROLE O9 ANTIBIOTICS

• Antibiotics are substances capable of destroying or inhibiting the growth of

bacteria

• They are chemicals that act on the pathogen without harming the host

• They are only e(ective against bacterial diseases, not viruses

• The 'rst antibiotic was )enicillin

• Antibiotics wor# internally on a cellular level




• @ecause of the widespread use of antibiotics however, some bacteria have

evolved resistant strains, which resist antibiotics

• In response, scientists have had to develop stronger antibiotics, however

problems may arise if the bacteria grows resistant to this stronger treatment

.> PROTECTING THE BODY: DE9ENCE BARRIERS

• The body has various defence mechanisms against pathogens

• 5irstly ! )rotecting the body at possible entry points, non-speci'c protection

which aim to prevent pathogens from entering the body

• 0econdly ! efence mechanisms operate when pathogens succeed in

entering the body, also non-speci'c response

• Thirdly ! 0peci'c defence mediated by lymphocytes

DE9ENCE BARRIERS = PREVENTING ENTRY

THE S;IN BARRIER

• 8icroorganisms cannot penetrate the s#in unless it is bro#en

• If the s#in brea#s, the blood clotting mechanism uic#ly forms a seal to

prevent entry of pathogens

MUCOUS MEMBRANES

• Dine the digestive, respiratory, reproductive, and urinary tracts with a thic#,

slimy mucous

• This mucous protects against invasion , aided by the presence of an antibody

in it which reacts to potential pathogens

SPECI9IC RESPONSES = THE IMMUNE RESPONSE

• The body&s immune response is its reaction to invasion by foreign materials

• These include viruses, bacteria, and to$ins

• The body identi'es these substances as foreign and triggers a response to

attempt to destroy them

• The substances which trigger this reaction are #nown as antigens

• This response can pose problems in organ transplants as the host&s body

identi'es the transplant as foreign, and attempts to attac# and destroy the

new tissue

DE9ENCE ADAPTATIONS = NON4SPECI9IC RESPONSES

IN9LAMMATION RESPONSE




• "hen any body tissue is damaged, the area becomes red, hot, swollen, and

painful

• @lood circulation to this area is increased and the blood vessels dilate and

become lea#y

• This response helps to con'ne the pathogen to one area of the body whilst

the body increases production of "hite @lood ells to destroy it• The chemicals histamine and prostaglandins are related to this response

PHAGOCYTOSIS

• )hagocytes are white blood cells which can actively move from the blood to

tissues, where they ingest and destroy any foreign material Fcontaining

foreign antigensH, including pathogens

• This action is #nown as phagocytosis

SEALING O99 THE PATHOGEN

• "hen the body is unable to neutralise an antigen, chronic in+ammation

involving macrophages FphagocytesH and lymphocytes Fproduced in the

lymph nodesH may occur

• The reaction forms a cluster of cells which surround the area of infection

.? THE IMMUNE RESPONSE

• "hen we are e$posed to an antigen for the 'rst time, our body responds by

producing lymphocytes

• Dymphocytes are a type of white blood cell, the two main types being T-ells

and @-ells

• Antibodies are produced by the @-ells in the lymph nodes in response to a

speci'c antigen entering the body

• Antibodies are proteins that bind to antigens, forming the antigen-antibody

comple$ which activates the production of proteins that results in the

ingestion and destruction of bacteria

T4CELLS

• There are four types of T-ells/ 7elpers Fstart immune responseH, ytoto$ic

Fattac# infected cellsH, 0uppressors Fsupresses immune responseH, and

8emory Faids pathogen immunityH

• T-ells form in the bone marrow, and mature and develop in the thymus

gland

• They remain inactive in blood until they come in contact with and antigen,

which binds onto the T-ell, activating it to multiply

• T ells control the cell-mediated response, in which various T ells destroy

the antigen or foreign cell




• *ther T ells stimulate the activity of @-ells and phagocytes, whilst some

remain in the body as T 8emory ells, which aid in the uic# removal of a

previously encountered antigen

THE ACQUIRED IMMUNE RESPONSE




• ytoto$ic T-ells destroy the cells which carry foreign antigens

• 7elper T-ells secrete chemicals which regulate cytoto$ic T-ell and @-ell

functions

• 0uppressor T-ells regulate @ and T ells, suppressing the immune response

once the pathogen has been destroyed

• 8emory T-ells recognise an antigen when it reappears and have the 7elpersuic#ly produce a large amount of antibodies

B4CELLS

• 8ature and develop in the bone marrow

• They control the blood response in which @ ells present in the blood and

lymph nodes are activated by the presence of antigens

• Activated @ ells clone themselves and then di(erentiate into either plasma

cells, which send antibodies to the blood, or memory cells

IMMUNITY AND IMMUNISATION PROGRAMS

• *nce a pathogen had infected the body and then been destroyed by it, the

infected person is said to be immune to that disease

• This immunity can be short-lived, or life-long

VACCINATION

• accination, or immunisation, is the process of ma#ing people resistant toinfections cause by pathogens

• It involves the administering of an in%ection or oral dose of vaccine

• accines are preparations of wea#ened or dead infective microorganisms that

are in%ected into the body to provo#e the immune response without causing

any symptoms

• 0ome vaccines wor# for life, whilst some much be readministered


)rimary infection

compared to secondary

infection after 8emory

ells have been created



• Active immunisation involves the in%ection of an antigen in the form of a

vaccine, which stimulates the @ and T 8emory ells speci'c to that antigen

• )assive immunisation involves the in%ection of antibodies that another

organism has produced in response to infection by a particular pathogen ! it

does not provide long term protection, however it is immediate

DELIBERATE SUPPRESSION O9 THE IMMUNE SYSTEM

• 0uppression of the immune system is necessary for the process of organ

transplants

• @ecause blood drains from the transplanted organ into the new host body,

the body recognises the cells as foreign and begins the immune response,

e(ectively attac#ing the new organ, aiming to destroy the tissue

• 4e%ection is reduced by matching transplanted tissue proteins to the

recipient&s proteins and by giving drugs to suppress the immune response

. EPIDEMIOLOGICAL STUDIES

6HAT IS EPIDEMIOLOGY

• Epidemiology is the study of diseases that a(ect many people, it describes

the patterns and cause of diseases in populations

• iseases studied include infectious diseases and those related to peoples&

life-style and environment

• They establish lin#s between lifestyle and disease eg. 0mo#ing and lung

cancer

• 8odern methods of epidemiological studies involve large groups of people to

collect a large, diverse uantity of information to be statistically analysed

• There are three broad categories of epidemiological studies/

• escriptive studies ! 0how patterns in the way diseases happen to be

distributed in populations

• Analytic studies ! )lanned investigations to test a speci'c hypothesis

• Intervention studies ! 8easure the e(ectiveness and safety of certain

interventions

LUNG CANCER

• aused by the abnormal growth of cells in the lung

• In 90" ??>, lung cancer was the most common cause of cancer deaths in in

people aged 2?-PK

• Epidemiological studies concluded that smo#ing is a ma%or cause of lung

cancer




• 5actors ta#en into consideration were the time one has been smo#ing,

cigarettes smo#ed each day, as well as other factors such as age, gender,

and year

CAUSES O9 NON4IN9ECTIOUS DISEASES

• 9ot caused by pathogens

• Include inherited diseases, nutritional de'ciencies, and environmental

diseases

INHERITED DISEASES

• Include gene and chromosome abnormalities and are genetically inherited

• They include minor disorders such a colour blindness, or ma%or disorders such

a cystic 'brosis

• They can be successfully treated by such things as surgery, drug treatment,

of special diets

• 7owever faulty genes cannot be corrected

NUTRITIONAL DISEASES

• Dac# of a vital component of diet. Eg. Dow vitamin can lead to 0curvy

CASE STUDY: SCURVY

• aused by a lac# of vitamin in the diet

• "as very prevalent in the time of sea e$ploration, where perishable food

items could not be ta#en

• It caused the capillaries to become fragile and bleed within the tissues, thegums to become swollen and rotten, teeth to fall out, wounds fail to heal, and

if untreated, death

ENVIRONMENTAL DISEASE

• an include e$posure to radiation, heavy metals, pollution in the air, soil or

water, lifestyle, loud noise, stress, and drug abuse

. STRATEGIES TO PREVENT AND CONTROL DISEASE

• There is a wide range of strategies to prevent and control disease in humans

PUBLIC HEALTH PROGRAMS

• 7elp to control and prevent disease by strategies directed at three targets;

the pathogen, the host, and the environment

• There is an increasing emphasis on )4EE9TI9 disease rather than

T4EATI9 it




• Daws reuiring government authorities to be noti'ed of the occurrence of

certain diseases has helped stop the spread of disease, reuiring people

e$hibiting the disease to be uarantined

• )eople are protected by improved awareness from public education

campaigns that in+uence people to improve their health. Eg. <Vuit= campaign

• accination programs and screening programs are also used to help preventdisease

QUARANTINE AS A CONTROL MEASURE

• Vuarantine is a period of isolation to prevent the spread of a contagious

disease

• Australia in particular has strict uarantine laws to protect the uniue plants

and animals from introduced species and disease

• Vuarantine inspectors patrol the entry of ships and aircrafts into Australia to

ensure the preventing of foreign disease entering the country

• Imported animals face a time in isolation and imported plants are e$amine toensure they bring no harmful substances

PESTICIDES

• hemicals that can destroy organisms that directly damage crops or plants,

or cause disease in livestoc# and animals

• They are also used to eliminate vectors eg. )otato leaf roll virus caused by

Aphids

• )esticides are often essential for the eLcient production of a healthy

agricultural crop, but their use may also cause environmental problems, such

as accumulation of pesticides in the food chain, and destruction of organismsother than those intended

• An e$ample is T, which used to be used as a common pesticide

• T does not brea# down easily, and stays in the environment for a long

period of time, poisoning soils and being carried around the world in water.

• T can have varying negative e(ects on organisms, for e$ample ma#ing the

shells of some bird eggs softer and more vulnerable

GENETIC ENGINEERING

• enetic engineering has produced disease-resistant plants and animals

• These plants and livestoc# have their genes altered to ma#e them resistant tocommon pests and diseases

• 7owever, genetic engineering remains a controversial topic

IMPLICATIONS 9OR THE 9UTURE

• The prevention and control of disease is a continuing battle




• In some areas, there has been immense success, such as the eradication of

smallpo$ and the decline of once-common human diseases through

vaccination programs

• 0ome controls wor# well for a time but then their e(ectiveness declines

• The development of drug resistance in pathogens means that without

continued research for new chemicals to destroy them, pathogens willcontinue to spread disease

OPTION 5: GENETICS: THE CODE BRO;EN

5.1 THE GENETIC CODE

DNA

9A Feo$yribonucleic AcidH is a double-stranded, helical molecule made up

of repeating units called nucleotides. FEach nucleotide contains a sugar,

phosphate, and a baseH

9A is able to replicate itself, so copies of a certain 9A molecule can be

made

enes are the particular seuences of bases along a 9A molecule

The information to create a new organism is transmitted by these genes

9A is present in almost every cell in an organism, contained mostly in the

nucleus

THE DNA CODE

The structure of 9A provides a code containing the information reuired to

produce a polypeptide




This 9A code is stored in the seuence of bases FA, T, , H in the 9A

strands

These bases code for amino acids, which form a chain to ma#e up

polypeptides

In humans, there are ? of these amino acids, and each is coded by a triplet

of bases called a codon The code determines/

>. "hich amino acids are put into the polypeptide. 7ow many amino acids in the polypeptide1. The arrangement of amino acids in the polypeptide

• 9ot all of the 9A functions as a code, the amount of genetic material in cells

greatly e$ceeds the amount of coded information used

• *nly some of this non-coding 9A is essential, the rest being regarded as

redundant& or %un#& 9A, however it may serve uses we do not yet #now

POLYPEPTIDE SYNTHESIS

• A gene is a region of 9A which controls inherited characteristics through

controlling polypeptide synthesis Fwhich fold to become proteinsH

• It does this by transferring coded information FbasesH to m49A, determining

the amino acids to be added in a polypeptide

• )olypeptide synthesis involves the following processes/

M. 9A ! A gene on the 9A strand provides the information reuired to ma#e

the polypeptideC. 8essenger 49A Fm49AH ! arries information from the 9A Fin the nucleusH

to the ribosomes in the cytoplasm Fas 9A cannot e$it the nucleusHP. Transfer 49A Ft49AH ! @rings amino acids to the ribosomes so they may be

able to be lin#ed together to build the polypeptide chain. Each t49A contains

an anti-codon which contains complementary bases to those found on the

m49AB. 4ibosomes ! Acts as a site for polypeptide synthesis in the cytoplasm as the

lin#ing of amino acids into a polypeptide

chain occurs>?.Enzymes ! Involved in catalysing the

reactions




STAGES O9 PROTEIN SYNTHESIS

TRANSCRIPTION

• The double 9A strand in the nucleus unwinds to form two strands with

revealed bases

• 49A then moves along one strand, lin#ing complementary 49A nucleotides

together to form a m49A strand F9@. There is a speci'c codon for the

beginning and end of the strandH

• After the entire gene is copied, the m49A moves from the nucleus to the

cytoplasm

ACTIVATION O9 AMINO ACIDS

• In the cytoplasm, an enzyme attaches amino acids to speci'c t49A molecules

TRANSLATION

• The m49A strand binds to a ribosome in the cytoplasm at the end of the

strand which e$presses the <0tart= codon FAH

• A t49A codon on the t49A strand carrying amino acids also binds to the

<0tart= codon within the ribosome

• The ne$t codon on the t49A strand is bound to the ne$t on the m49A strand

and the amino acid is holds is bound, via peptide bond, to the 'rst amino acid

• The 'rst t49A codon is then released from the ribosome, and the ribosome

continues along each strand, continuing this process to form a polypeptide

chain Fa chain of bounded amino acidsH

• *nce the <0top= codon on the m49A is reached, the polypeptide chain is

released into the cytoplasm

• The chain then undergoes speci'c twisting, folding, and shape changing to

eventually form a protein




GENE E7PRESSION

• A gene undergoing these processes is said to be being <e$pressed=, the code

being used to ma#e a polypeptide

• "e can see this gene e$pression in the phenotype of a cell or organism, that

is, the observable, physical features

5.5 VARIABILITY 6ITHIN A TRAIT




MULTIPLE ALLELES

i(erent forms of a gene that in+uences one characteristic are called alleles

Each individual can have two alleles for a particular gene, one on each

homologous chromosome

"hen more than two alleles in+uence one trait, they are called multiplealleles

In this case, one allele is normally dominant to a series of recessive alleles,

each with varying degrees of dominance over the others

An e$ample of this is in rabbits, whose coat colour is controlled by K di(erent

alleles

They show the following seuence of dominance/ Ag S h S 7i S Al

THE INHERITANCE O9 BLOOD GROUPS IN HUMANS

• In humans, there are several blood groups under which blood can be

identi'ed• This is determined by the A@* and 4hesus systems

• These systems are important as during blood transfusions, an incorrect blood

group could be fatal, due to a reaction similar to the antigen-antibody

reaction

ABO GROUPS

• In the A@* system, there are four blood groups/ A, @, A@, and *

• There are three alleles for this system/ A, @, and *

• A and @ are completely dominant over *, however are co-dominant to each

other, put simply,A R @ S *

• This means that people of the blood group A can have the genotype AA or

A*, whereas people of the blood group * can only have the genotype **

THE RHESUS BLOOD GROUP

• The second system of blood grouping is based on the rhesus factor, and is

represented by a <= or a <-< following the A@* group

• The rhesus For 4hH factor is coded by two alleles, and so relies of simple

ominantG4ecessive inheritance, the <= allele being dominant to the <-<

allele

POLYGENIC INHERITANCE

• In many cases, a trait FphenotypeH is not e$pressed by only one gene, but a

combination of many genes, or polygenes, located on di(erent chromosomes




• )olygenic inheritance is especially noticeable in height in humans, with

overall height being a(ected by many di(erent characteristics F7eight of/

nec#, body, head, legs etcH

DNA 9INGERPRINTING

• All organisms produced by natural se$ual reproduction have uniue 9A

• Although it is the coding regions of 9A Fthe e$onsH which ma#e up an

organism, it is the non-coding regions Fthe intronsH that are able to be used to

uniuely genetically identify an individual ! This is #nown as 9A

5ingerprinting

• 4ecombinant 9A technology allows the 9A of an organism to be analysed

and compared with other 9A samples

• 9A 'ngerprinting can be used in medicine, genetics research, and forensic

science

5.< INHERITANCE O9 GENES

MEIOSIS

• The traits of o(spring re+ect the inheritance of genes from the parents




• 8eiosis is a type of cell division which occurs during se$ual reproduction,

resulting in the splitting of a somatic FdiploidH cell into two haploid cells

• Three di(erent outcomes occur as a result of meiosis/a. enes on di(erent chromosomes are inherited according to 8endel&s

laws

b. enes on the same chromosomes are inherited together, their traitsusually occurring together. This is #nown as DI9NE

c. enes on chromosomes that cross over create new combinations of

traits in the o(spring

DIHYBRID CROSSES

• 8endel also carried out e$periments involving two characteristics, #nown as

dihybrid crosses

• 5or e$ample, crossing reen 4ound peas with :ellow "rin#led peas FTwo traits

being crossedH

•

"hen heterozygous organisms are crossed, they give a ratio of B/1/1/>

• FThis is a heterozygous cross ! g4r -S 4, r, g4, grH

MENDELS LA6S

8endel studied the inheritance of genes on di(erent chromosomes using

monohybrid crosses

7e summarized his 'ndings into two laws/

The Daw of 0egregation/ The alleles of a gene pair separate at gamete

formation so that each gamete contains only one allele of each gene pair

The Daw of Independent Assortment/ Each gene pair sorts out independently

of other gene pairs at gamete formation ! meaning that either allele of a

gene pair can combine with either allele of another gene pair

LIN;ED GENES

• The genes on any given chromosome are usually inherited together and

therefore said to be lin#ed

• If genes for colour and shape, for e$ample, were on the same chromosome,

they would not separate independently, and would pass directly into the

gametes together




• 7owever lin#ed genes can be separated from each other in meiosis if crossing

over occurs, the further apart they are on the chromosome, the more li#ely

they will separate

CHROMOSOME MAPPING

• hromosome mapping gives us a picture of the arrangement of an

organism&s genes on its chromosomes

• If genes are close together on a chromosome, they usually stay together

during meiosis

• 0tudying the freuency of recombination of traits in breeding e$periments

has allowed scientists to produce maps of the genes on chromosomes

• The formula for estimating the distance between two genes on a

chromosome is/

• These maps provide an insight into genetic lin#age and show the relative

distance between genes

• Today, recombinant 9A technologies can produce more accurate maps

showing the position of genes in term of the seuence and number of bases

involved

RELATIONSHIP BET6EEN SPECIES

•

*rganisms of the same species share a common gene pool and have similarchromosome maps

• The more closely related organisms are, the more genes they have in

common

• The identi'cation of lin#age groups Fgrouped genesH in di(erent organisms is

one method of analyzing these relationships between species

• Evidence of similarities in lin#age groups between species indicates the

possibility that each organism shared a common ancestor

• ltimately, chromosome mapping of gene lin#age provides another source of

evidence for the evolution of living organisms

5.> THE HUMAN GENOME PRO@ECT

• The genome of an organism is all the genetic material of an individual or

species

• In a haploid Fhalf the total amount of chromosomesH, the human genome

consists of about 1 billion 9A bases arranged along the chromosomes




• The 7uman enome )ro%ect F7)H is an international pro%ect which aimed to

identify all the human genes and to determine the seuences of these 1

billion bases in human 9A

• >P countries participated in the 7) Fthis included Australia, The 0A, Uapan,

the E, hina, N, Italy, and 5ranceH

• The pro%ect began in >BB? and aimed to ta#e >2 years to complete, however'nished years early in ??1, achieving the goal of completely identifying

the human genome

• This achievement was made possible largely by rapid advancements in

technology

• A collaborative approach was also ta#en, which allowed the results to be

more uic#ly obtained and wor# together, each participating country being

assigned a particular tas#

• These tas#s included/

>. enetic mapping of the human genome. )hysical mapping of the human genome

1. 9A seuencingK. Analysing the genomes of other organisms

BENE9ITS O9 THE HUMAN GENOME PRO@ECT

• The bene'ts of the 7) will be enormous to advancing our #nowledge and

technology in biology and medicine, as detailed 9A information will be

available in further research

• In medicine, the bene'ts include signi'cantly aiding in diagnosing, treating,

and preventing disease F5or e$ample, insulin bacteriaH

• )eople with family history of a particular disease are also able to 'nd out

whether or not they carry the diseased genes, resulting in faster diagnosis

and uic#er prevention of diseases

• In the future, this may lead to the ability to identify disease-causing genes in

a foetus and splice out the defective alleles

• @iologically, the 7) allows for more detailed comparisons to be made

between species and improved and easier genetic research

LIMITATIONS O9 THE PRO@ECT

• espite providing a signi'cant leap in our understanding of the human

genome, the 7) is loo#ed at as preliminary data, and not a 'nal

understanding of cell and organism functioning

• "hat we do with this preliminary data provides the real challenge, as simply

#nowing the base seuences does not determine the functioning of every

gene




• Ethical, legal, and social implications and issues also arise from the possible

information gathered as a result of the 7)

PRODUCING RECOMBINANT DNA

4ecombinant 9A is produced in cells as a result of chromosome crossing-

over in meiosis

@efore the 7), this could only be achieved through the deliberate crossing

of organisms, however now, recombinant 9A is able to be produced in a lab

using molecular technologies

4estriction enzymes cut pieces of 9A, and are resealed to other pieces of

9A using sealing enzymes to form new recombinant 9A

E7AMPLE: INSULIN

>. The human gene for ma#ing insulin is cut out of the chromosome ta#en from

a human pancreas cell FIslets of Dangerhans cellH using an enzyme called

restriction enzyme.. A ring of 9A called a plasmid is removed from the E.coli bacterium and cut

open with a restriction enzyme.1. The human insulin gene is mi$ed with the cut plasmid. All of the cut ends

FWstic#y endsWH can bond together using the enzyme 9A ligase to ma#e a

new 9A molecule.K. The WnewW plasmid, that contains the recombinant 9A, is inserted bac# into

the bacterial cell.2. "hen the bacterial cell reproduces, so does the plasmid and hence the

human insulin gene. "hen provided with the appropriate nutrients, these

cells produce human insulin which can be e$tracted and used by diabetics.

E7AMPLES O9 RECOMINANT DNA TECHNOLOGIES

• utting and re%oining 9A using restriction enzymes and sealing enzymes

• se of vectors to act as carriers of 9A fragments or genes

• )olymerase chain reactions to produce multiple copies of 9A

• 9A hybridization

• se of genetic probes Fradioactive segments of 49A or 9AH which are

complementary to a 9A seuence being sought

MAPPING GENES USING RECOMBINANT DNA TECHNOLOGY

• 4ecombinant 9A has played a large part in mapping genes on chromosomes

• sing lin#age studies in the >BP?s, scientists were able to construct genetic

maps using genetic mar#ers&, regions of 9A that were either e$ons or

introns Fcoding or non-codingH




• 8ar#ers that usually occurred together were assumed to be determined by

genes on the same chromosome and were said to be lin#ed

• These lin#age maps however, only showed relative positions of the mar#er

regions, and so genetic mapping using new technology enabled the rapid and

accurate advancement of the 7)

• Two such technologies were 4estriction 8apping, and 9A 0euencing

5.? GENE THERAPY

If faulty genes can be replaced, switched o(, or corrected, then diseases can

be treated at its source ! this method of treatment is #nown as gene therapy

ene therapy becomes possible only when the genes responsible for the

harm are identi'ed

It represents a more eLcient way to diagnose, treat, and prevent disease,

however, is still largely e$perimental

In short, gene therapy aims to replace faulty genes with healthy ones

There are several steps the need to be followed to achieve this/o Identi'cation of the disease-causing gene

o Docation of cells or tissues involved in the disease

o Access to multiple copies of the normal gene

o Insertion of the normal gene into the a(ected cells

8ost commonly, viruses are used as vectors to carry the replacement gene to

a cell, the virus being in%ected with the normal gene, and then the human

being in%ected with the virus

"hilst this is the most eLcient way, it also poses ris# as viruses are

commonly pathogens themselves

9on-viral methods, such as direct introduction, nanotechnology, and

constructing arti'cial chromosomes are also being used, however none are ase(ective as the viral method

5. GENETIC CHANGE

• Any permanent change in the 9A is called a mutation

• A mutation therefore, can involve changes in either the chromosome, or a

single gene

CHROMOSOME MUTATIONS

•

0ome mutations involve a change in chromosome number, which arisesthrough an abnormality in meiosis, leaving the person with either too many

or too few chromosomes

• In most cases, this occurs prior to gamete formation, and the gametes

produced do not produce viable o(spring on fertilization

• In own&s 0yndrome, three copies of chromosome > are inherited, resulting

in a total of KC chromosomes in the o(spring, this is #nown as Trisomy




• Another chromosome mutation is )olyploidy, which results in an individual

having whole e$tra sets of chromosomes, possibly resulting from improper

separation in mitosis

• )olyploidy is much more common in plants and often results in larger,

stronger plants

• In animals however, polyploidy is fatal• )arts of a chromosome may also be rearranged and the seuence of 9A

altered, causing visible changed in the chromosome structure

GENE MUTATIONS

8utations may often not be large enough to a(ect chromosome structure, but

can be as small as to a(ect only a single base, or the involve a whole gene

9A seuence

There are two main types of gene mutations, base substitution, and

frameshift mutations

@ase substitution is when a single base may be replaced by another, causinga point mutation which changes codons, and by e$tension, disrupts normal

amino acid production

5or e$ample, AT might change to A. These codons each code for a

di(erent amino acid and so regular bodily functioning is a(ected

espite this, some base substitutions can result in no amino acid change, or

an amino acid change with no visible e(ect to the organism

5rameshift mutation occurs when a single base is added or deleted from a

9A seuence

This loss or addition results in a change in the codon seuence after it has

occurred, thus a(ecting amino acid production and the functioning of

produced proteins

5or e$ample, the seuence T7E 5AT AT ATE T7E 8AT, would change to T7E

55A TA TAT ET7 E8A T, if an e$tra 5 was added after the 'rst codon

• ystic 5ibrosis F5H is a disease caused by gene mutation, most commonly a

base deletion Fframeshift mutationH from chromosome C

• 8utations can occur spontaneously during 9A replication, and the rate can

be increased by environmental factors such as radiation, chemicals, or

viruses

DNA REPAIR AND MAINTENANCE

• hanges that occur to the 9A in a fully di(erentiated specialized cell may

lead to the malfunctioning or death of that cell




• In dividing cells, it is important that 9A is chec#ed and repaired, if

necessary, by 9A repair genes to ensure healthy, somatic cells

• This repair reduces the chance of continuing a possible harmful mutation that

has arose in a cell

@UMPING DNA

• Uumping 9A refers to the idea that some pieces of 9A are transposable,

they can move from one position in the 9A to another

• 8any types e$ist, di(ering in length and behavior, but their movement is not

common

• As well as moving themselves, %umping 9A can rearrange neighboring

segments of 9A due to deletion, addition, or relocation of some bases

• Uumping 9A are li#ely to have played a ma%or role in the evolution of life on

earth, as they/o estabilise the 9A in cells

o eregulate the reading of geneso @ecome active in bursts after periods of inactivity, causing several

characteristics to change at the same time

• Transposable elements F%umping 9AH is thought to be lin#ed so some

genetic diseased such a breast cancer and leu#emia

GERM LINE AND SOMATIC MUTATIONS

• 8utations that arise in an organism&s somatic cells Fbody cellsH a(ect only the

organism in which the mutation occurred. This is common in cancers and is

#nown as somatic mutations

•

erm line mutations however, arise in an organism&s germ cells Fcells thatform sperm or eggsH and so will be passed on to, and a(ect the o(spring,

possibly causing inherited diseases

• A favorable germ line mutation provides the basis for natural selection and

the evolution of a species, however favorable mutations are much more rare

than unfavorable

5. SELECTIVE BREEDING

0elective breeding is the practice of choosing individuals in a population of a

species for mating, to obtain o(spring with certain characteristics

4epetition of this will result in a population in which the ma%ority ofindividuals e$press these desired characteristics

7umans have been controlling the breeding of domestic animals and plants

in this way for thousands of years, particularly today in livestoc# and

agriculture to produce animals and plants as superior food sources




6HEAT BREEDING

• In terms of volume, wheat is the more important agricultural crop in Australia

• The selective breeding of wheat has been practiced in Australia since the

times of the early settlers, as European wheat did not grow e(ectively in

Australian conditions• *ver time, wheat has been bred to have certain characteristics and provide a

ma$imum yield. 0ome of these characteristics are/o 4apid progression through life cycle

o Increased grain yield

o isease resistance, particularly to rust fungi

o Increased tolerance to frost, drought, and acidic soils

o Improved +our uality

• "heat in Australia has changed dramatically from the time of European

settlement, as humans have cross-bred many di(erent species to end up with

a species of wheat best suited to both the environmental conditions and the

needs of the human population• 5or e$ample, in the early >B??s, wheat was cross bred with Indian wheat to

increase rust resistance and shorten ripening time

• 5ederation& "heat is a notable e$ample from the >B?s, being a wheat

cultivar, that is it cannot be found in the wild and has been selectively bred

for speci'c characteristics

GENE CLONING

• A clone is an e$act genetic copy, and 9A, cells, and whole organisms can be

clones

•

ene cloning uses genetic engineering techniues to produce unlimitednumbers of identical copies of genes ! clones

• A number of recombinant 9A technologies may be used in cloning, for

e$ample, genes can be inserted into bacteria, which multiply to produce

more than billions of copies of the inserted gene

• )olymerase hain 4eaction F)4H is the newest and fastest form of gene

cloning

• ene cloning has many practical uses, particularly in research, forensics, and

medicine

6HOLE ORGANISM CLONING

• "hole organism cloning is a method of reproduction that results in

genetically identical o(spring which are e$act genetic copies of the parent

• )lants can be cloned using a tissue culture, cells ta#en from the parent plant

being grown into a whole plant

• Animals however, reuire a nuclear transfer, where the entire genome FKM

chromosomesH from a cell of the parent is inserted into an egg cell that has

had its nucleus removed




• The egg cell is then implanted into a surrogate mother where is develops

normally

• The o(spring that results is a genetically identical copy of the parent animal

5. DEVELOPMENT

EMBRYONIC DEVELOPMENT

GENE CASCADES IN LIMB 9ORMATION

• All animals have at least one cluster of homeotic genes Fgenes that

determine what parts of the body form what body partsH that lay down the

pattern for the front-to-bac# body a$is

• In vertebrates, the development of the body and limbs is always organized

the same way, the body developing from head to tail and limbs from the base

to the tips

EVOLUTIONARY RELATIONSHIP REVEALED BY HOMOLOGY




The evolution of life on Earth over billons of year has produced tremendous

variation in the appearance of living things

7owever, studies in comparative anatomy, such as that of the pentadactyl

limb have revealed similarities between what would otherwise be considered

very di(erent organisms

omparative embryology has shown how di(erences in an initially similarstructure appear as development proceeds

As scientists delve further into comparing the inner wor#ings and

biochemistry of organisms, the common origins of living things is revealed

repeatedly

It has been shown that nucleotide seuences in the genes of di(erent

organisms is e$tremely similar

5or e$ample, the enzyme needed for a particular reaction in the respiration

pathway in bacteria has a similar structure to humans

This similarity provides evidence for evolutionary relationships between these

organisms and so is another point of evidence for evolution, particularly from

a common ancestor

THE EVOLUTION O9 GENES

• urrent research suggests that many gene contain nucleotide seuences that

have changed only slightly and slowly during the evolution of life on Earth

• 5or this reason, they are able to be used to compare relationships and

relatedness between organisms, as they would not have changed much since

their time of creation

• @ecause the homeobo$ seuence Fclosely similar seuences that occur in

various genes and are involved in regulating embryonic developmentH is

similar in 7o$ genes, it is thought that they are homologous genes and all

share a common ancestral gene

• 7o$ genes are also arranged in clusters on chromosomes and can be found in

similar positions within these clusters across the animal #ingdom

• @ecause of this, it seems li#ely that all animal species inherited their 7o$

genes from a common ancestor

• The study of mutations in homeotic genes show that a small mutation can

result in a dramatic and sudden change in an organism as the developmental

cascade is altered

• The study of the evolution of gens, particularly homeotic genes, and the

e$pression of genes, particularly during development, is giving us anunderstanding of their e(ects on living organisms and providing new

information about evolutionary relationships




END O9 HSC COURSE

2014 biology notes

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