ib biology joni rogan escuela de lancaster a.c.. course outline - theory 1: the chemistry of life ...
TRANSCRIPT
IB BiologyIB Biology
Joni Rogan
Escuela de Lancaster A.C.
Course outline - Theory1: The chemistry of lifeStatistical analysis2: Cells 3: Genetics4: 5: Ecology and evolution 6: Human health and physiology
Theory AssessmentMakes up 76% of final grade3 exam papers:
Paper 1- 30 MCQ Paper 2- data based Qs, Extended
response Paper 3- short answer questions
Course Outline- PracticalPracticals make up 24% of final grade.The marks are in 2 parts:
Investigations Group 4 projects
InvestigationsThroughout course as fits with theory
You are assessed on 2 examples of each of the following: Design Data collection Concluding Evaluating
Group 4 ProjectsCross-curricular Science project in
small groups (with Chemistry and Physics)
You design and carry out an investigation on a theme
You are marked on: Manipulative skills Personal skills
To do well in IB Biology.....Work hard and learn at home
throughout the year
Use the rubrics
Learn the command terms
Take the practical work seriously
Biological MoleculesTopic 1
What are living things made of?4 most commonly occuring elements?Other elements?
Element Role served in living things
Sulfur Component of amino acids
Phosphorus Component of nucleotides in DNA and RNA
Iron Role in oxygen transport in animal blood.Component of cytochrome proteins involve in electron transport in plants, animals and prokaryotes
Sodium Role in nerve impulse in animals.Essential for maintaining metabolic activities in some bacteria.
Calcuim Component in strengthening bones and teeth.
What are elements are made of?Chemistry revision!
What are we made of?
Richmond upon Thames College
Introduction For each of the following you should be able to:
Describe the properties Know the general formulae & structure Understand the role in animals & plants
•Water
•Carbohydrates
•Lipids
•Proteins
•Nucleic acids
Water
What is it made of?
How is it chemically arranged and held together?
What does this mean for how it behaves?
How is this useful for life?
WaterWater is a polar molecule It forms weak hydrogen bonds It remains a liquid over a wide
temperature rangeWater molecules stick to one another =
cohesion (surface tension)Water molecules stick to other
substances = adhesion (capillarity)
O
H
H
+
+-
Water It has a high specific heat capacity – so
water can maintain a reasonably constant temperature (homeostasis)
It has a high latent heat of vaporisation – so animals use water to cool themselves
It is less dense as a solid (ice)…… and ice is a poor conductorWater is a good solvent
Property Chemistry Use in living organism
Cohesion Water molecules stick to each other because of Hydrogen bonds
Water is used as a transport medium in the xylem of plants, it can be pulled up tall plants.
Solvent Waters’ polartiy means it can dissolve particles with positive or negative charges or other polar molecules.
Water is the medium for metabolic reactions. It also can be used as a transport medium.
Thermal Water has a large heat capacity, high energy is needed to break the Hydrogen bonds.
Blood (mainly water) can carry heat from warmer parts of body to cooler parts.Water is most useful as a liquid, and is a liquid in most parts of the earth.When water evaporates, energy to break Hydrogen bonds comes from the liquid water, which cools it down. So water can be used as a coolant.
Carbohydrates Contain the elements Carbon
Hydrogen & Oxygen There are 3 types:
Monosaccharides Disaccharides Polysaccharides
Monosacharides
(CH2O)n
If n=3, triose (glyceraldehyde) If n=5, pentose (fructose, ribose) If n=6, hexose (glucose, galactose)Monosaccharides are used for
Energy Building blocks O
C C
C C
C
C
IsomerismThey can exist as isomers:
& glucose OH
OH
DisaccharidesFormed from two monosaccharidesJoined by a glycosidic bondA condensation reaction:
glucose + glucose maltose glucose + galactose lactose glucose + fructose sucrose
Condensation reaction
O
C C
C C
C
CO
C C
C C
C
C
OH OH
Condensation reaction
O
C C
C C
C
CO
C C
C C
C
C
OH OH
Condensation reaction
O
C C
C C
C
CO
C C
C C
C
C
O
H2O
Condensation reaction
O
C C
C C
C
CO
C C
C C
C
C
O
A disaccharide1,4 glycosidic bond
41
PolysaccharidesPolymers formed from many
monosaccharidesThree important examples:
Starch Glycogen Cellulose
Starch Insoluble store of glucose in plantsformed from two glucose polymers:
Amylose
-glucose
1,4 glycosidic bonds
Spiral structure
Amylopectin
-glucose
1,4 and some 1,6 glycosidic bonds
Branched structure
Glycogen
Insoluble compact store of glucose in animals
-glucose units1,4 and 1,6
glycosidic bondsBranched structure
CelluloseStructural polysaccharide
in plants-glucose1,4 glycosidic bondsH-bonds link adjacent
chains
O
O
O
O
O
LipidsMade up of C, H and OCan exist as fats, oils and waxesThey are insoluble in waterThey are a good source of energy
(38kJ/g)They are poor conductors of heatMost fats & oils are triglycerides
TriglyceridesFormed by esterification……a condensation reaction between 3
fatty acids and glycerol:
Glycerol
H
C
H C
C
H
H
H
H
O
O
O
Fatty acidsCarboxyl group (-COOH) attached to a long non-polar
hydrocarbon chain (hydrophobic):
H
H
C
HH
C
H
H
C
HC
O
O
H
C
HH
C
H
H
C
H
H
C
H
H
A saturated fatty acid (no double bonds)
HH
C
O
O
H
C
HH
C C
C C H
C
H
H
C
H
HA polyunsaturated fatty acid
C
O
O
H
C
HH
C
H
H
C
H
H
C
H
C
HH
C
H
H
C
H
H
A monounsaturated fatty acid
H H
Esterification
H
C
H C
C
H
H
H
H
O
O
OC
O
O
H
C
HH
C
H
H
C
H
H
C
H
H
Glycerol Fatty acid
Esterification
H
C
H C
C
H
H
H
H
O
O
OC
O
O
H
C
HH
C
H
H
C
H
H
C
H
H
Glycerol Fatty acid
Esterification
H
C
H C
C
H
H
H
H
O
O
OC
O
O
H
C
HH
C
H
H
C
H
H
C
H
HGlycerol Fatty acid
Esterification
H
C
H C
C
H
H
H
H
O
O
OC
O
O
H
C
HH
C
H
H
C
H
H
C
H
H
Ester bond
water
EsterificationThis happens three times to form a
triglyceride:
glycerol fatty acids
PhospholipidsOne fatty acid can be replaced
by a polar phosphate group:
glycerol Hydrophobic fatty acids
hydrophilicphosphate
Functions of lipidsProtection of vital organsTo prevent evaporation in plants &
animalsTo insulate the bodyThey form the myelin sheath around
some neuronesAs a water source (respiration of lipids)As a component of cell membranes
Research Topics1) Hydrogenated fats
What are they? What foods are they in? How do your bodies deal with them? Why do some people want them banned?
2) Atkins Diet
Why does the diet get people to lose weight? What is the difference between how carbohydrates and fats are stored and metabolised? Why are Doctors worried about people on the diet?
Proteins Made from C H O N & sometimes SLong chains of amino acidsProperties determined by the aa
sequence
Amino acids
H
CH
N C
HH
O
O
R
~20 aaGlycine R=HAlanine R=CH3
aminecarboxyl
Peptide bonding
HC
HN C
HH
O
O
R
HC
HN C
HH
O
O
R
Peptide bonding
HC
HN C
HH
O
O
R
HC
HN C
HH
O
O
R
Peptide bonding
H
CH
N C
HH
O
O
R
HC
HN C
HH
O
O
R
Peptide bonding
CH
N C
HH
OR
HC
HN C
H
HO
H
O
O
R
water
Peptide bond
A condensation reaction
Peptide bonding
CH
N C
HH
OR
HC
HN C
H
O
O
R
A dipeptide
Primary structureThe sequence of aas is known as the
primary structureThe aa chain is a polypeptide
Secondary structureH-bonding forms between adjacent aa
R groupsThis results in the chains folding:
Secondary structure
-helix -pleated sheet
Tertiary structureBonding between R-groups
gives rise to a 3D shapeH-bonds =O HN-
Ionic bonds –NH3-COO-
Disulphide bridge
--CH2S-SCH2-
affected by temp & pH
affected by pH
affected by reducing agents
Quaternary structureSome proteins have
more than one polypeptide chain
Each chain is held together in a precise structure
eg Haemoglobin
Types of proteinsFibrous proteins
e.g. collagen Insoluble structural
Globular proteins e.g.enzymes Soluble 3D shape
Functions of proteins Enzymes – Transport – Movement – Cell recognition – Channels – Structure – Hormones – Protection –
Amylase
Haemoglobin
Actin & myosin
Antigens
Membrane proteins
Collagen & keratin
Insulin
Antibodies
Nucleic acidsDNA & RNAMade up of nucleotides:
phosphate
pentose sugar
base
Nucleotides2 types of base:
Pyrimidines - Cytosine C Thymine T
Purines Adenine A Guanine G
Complimentary base pairingAdenine will only bind with ThymineCytosine will only bind with Guanine
T C GA
DNA structure
nucleotide
Condensation polymerisation of the deoxyribose nucleotides
Questions What things must DNA be able to do to allow an
organism to survive?
How is it possible that DNA can control all of the chemical reactions occurring inside a cell?
What type of protein molecules control DNA replication (can you name any specific ones)?
Why is DNA replication called “semi-conservative”?
Replication During cell division the DNA must replicate The DNA double helix unwinds (helicase
enzyme does this) at the replication fork The exposed bases bind to free floating
nucleotides in the nucleoplasm The enzyme DNA polymerase binds the
complimentary nucleotides Replication is
semiconservative
ReplicationDNA polymerase can only work in one
directionTherefore on one DNA strand
replication occurs in small sections called okazaki fragments
The okazaki fragments are then joined together by an enzyme called DNA ligase
Questions Briefly explain the purpose of DNA replication Summarise the steps involved in DNA
replication (3) Explain the jobs of the following enzymes:
Helicase DNA polymerase
How long do you think it would take for one bacterial cell to replicate all of its DNA?
The genetic codeThe sequence of nucleotide bases
forms a codeEach ‘code word’ has three letter – a
triplet codeEach codon codes for a specific amino
acid e.g: GGG = proline CGG = glycine ATG = tyrosine ACT = stop (no amino acid)
Protein synthesisThe DNA codes for
proteinsA copy of DNA
(mRNA) is made in the nucleus (transcription)
The mRNA is used to make a protein (translation) in the cytoplasm
Transcription The DNA unwinds Only one DNA strand will
be transcribed (the sense strand)
Free nucleotides join onto complimentary bases
RNA polymerase links adjacent nucleotides
The completed mRNA moves out of the nucleus
In RNA there is no thymine (T). Instead, another base, uracil (U) takes its place. U forms hydrogen bonds with A
Transcription
Amino acid activation transferRNA:
tRNA binds onto a specific amino acid
TranslationmRNA binds to a ribosome tRNA carries an amino acid to the
ribosome
TranslationA second tRNA brings another aaThe two aa’s bindThe process repeats
TranslationA polypeptide chain formsEventually a stop codon is reached
The Human Genome Project A multinational project aimed at sequencing
the entire human genome Visit the Human Genome Web site:
www.ornl.gov/hgmis/project/about.html www.sanger.ac.uk
Acknowledgements Animated cell models used by kind
permission of The Virtual Cell website:
Feel free to use this presentation for educational non-profit making purposes.
Quiz 1. Which of the following is not an
important property of water
a) Its polar nature
b) Its low specific heat capacity
c) Its high latent heat of vaporisation
d) Its low density in solid form
Quiz 2. The general formula for a
monosaccharide is:
a) (CH2O)n
b) (CHO)n
c) C(H2O)n
d) CnH2On
Quiz 3. Sucrose is made up of
a) glucose + fructose
b) glucose + galactose
c) glucose + glucose
d) galactose + fructose
Quiz 4. Amylopectin is made up of:
a) -1,4 glycosidic ondsb) -1,4 & -1,4 glycosidic ondsc) -1,4 & 1,6 glycosidic ondsd) -1,4 & 1,6 glycosidic onds
Quiz 5. Formation of a triglyceride does
NOT involve:
a) A condensation reaction
b) Esterification
c) Polymerisation
d) A reaction between 3 fatty acids & glycerol
Quiz 6. The general formula of a saturated
fatty acid is:
a) CnH2nO2
b) Cn(H2O)n
c) (CH2O)n
d) (CH2)nO
Quiz 7. Which of the following is not
responsible for a proteins tertiary structure
a) ionic bonding
b) covalent bonding
c) hydrogen bonding
d) disulphide bonding
Quiz 8. Which of these is not an amino
acid:
a) alanine
b) cysteine
c) glycine
d) cytosine
Quiz 9. Which process involves tRNA:
a) transciption
b) translation
c) DNA replication
d) gene mutation
Quiz 10. The formation of RNA does not
involve:
a) ribose sugar
b) thymine
c) removal of water
d) phosphate