What is What is Biology?Biology?What is What is Biology?Biology?

What is Biology, you ask?What is Biology, you ask?

Biology is the study of life.Living things are called organisms.

Organisms include bacteria, protists, fungi, plants, and animals.Viruses are not alive – they are not organisms.

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The seven characteristics The seven characteristics of lifeof life

All life is made of cells.All life must reproduce.All life has heredity based on one universal genetic code (DNA).All life has metabolism.All life must respond to environmental stimuli.All life has homeostasis; it must maintain

a stable internal environment . All life must evolve; that is, species must change over time.

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All organisms are made of All organisms are made of cellscells

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All organisms are made of All organisms are made of cellscellsCells are the building blocks of life.All cells come from pre-existing cells.

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Viruses (in red here) are not made of cells; they are not alive.Viruses (in red here) are not made of cells; they are not alive.

The cell theory states that

all living things are made up of cells; basic units of structure and function in living things are cells that new cells can only be produced from living, existing cells.

Biochemical Biochemical ReactionsReactionsBiochemical Biochemical ReactionsReactions

Cells can undergo chemical reactions that release energy from carbon-containing compounds (organic) as food.There are 3 major classes of organic molecules:

CarbohydratesProteinsLipids

CarbohydratesCarbohydratesInclude sugar – C6H12O6

Formed from photosynthesisBroken down in cellular respirationEquation: Photosynthesis6CO2 + 6H2O → C6H12O6 + 6O2

Equation: Cellular Respiration

P + ADP + C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP

ProteinsProteinsNeeded:

to access energy stored in cellsto build cell structuresto regulate rate of chemical reactions

LipidsLipidsCommonly known as fats and oilsCreate membranes of cells that provide sites for essential energy conversions.Refer to figure 1 in the packet

Cell membraneCell membraneSeparates the living from non-living

environment.

Made of proteinand lipidMade of proteinand lipid

Cell membraneCell membraneA cell must be able to obtain food

and get rid of wastes through its cell membrane

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DiffusionDiffusionThe movement of particles from a region

of high concentration to a region of low concentration.

Examples: perfume in air, smoke in air, sugar in water,

oxygen through cell membranes

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OsmosisOsmosisDiffusion of water from an area of high

concentration of water molecules to one of low concentration across a partially permeable membrane.

Partially permeable means only some things can pass, not everything: usually small molecules with no charge, like H2O, CO2, & O2.

“High” water concentration means that there are a lot of water molecules per some unit of volume.“Low” water concentration means that

there is a lot of something dissolved in the water, so fewer molecules

of water.15

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Comparison ofComparison ofPhotosynthesis and Cellular Photosynthesis and Cellular

RespirationRespirationDiscuss Table 1Photosynthesis

6CO2 + 6H2O → C6H12O6 + 6O2

Cellular Respiration

P + ADP + C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP

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All life has metabolismAll life has metabolismCellular Respiration (in Mitochondria)

Through respiration, cells release the chemical energy stored in foods created by photosynthesis.

6O2 + C6H12O6 6CO2 + 6H2O + 36 ATP

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All life has metabolismAll life has metabolismSunlight is the ultimate energy for life on

Earth. Photo-synthesis is carried

out in the chloro- plast

of producers such as algae, phy- toplankton, plants.

Asexual and Sexual Asexual and Sexual ReproductionReproductionAsexual and Sexual Asexual and Sexual ReproductionReproduction

Asexual ReproductionAsexual ReproductionOne parent passes copies of all its chromosomes to each of its offspring.Organisms produce new cells by mitosis.Mitosis is the process of nuclear division in which 2 new daughter cells each receive a complete set of chromosomes.Offspring are genetically identical to each other and the parent.Examples: Refer to table 1video

Sexual ReproductionSexual Reproduction

Involves two parentsThe offspring receives half of its chromosomes from the father and half from the mother.Gametes are sex cells (eggs – sperms)Meiosis produces gametes (1/2 # chromosomes)

Upon fertilization, full number of chromosomes is restored with the formation of a zygote.

A zygote contains all the information necessary for growth, development, and reproduction.The zygote will be similar but not identical to its parents.

All organisms must All organisms must reproducereproduce

For sexualFor sexualreproductionreproduction

For asexualFor asexualreproductionreproduction

Gametes

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Punnett SquaresPunnett SquaresGenotype – genetic characteristics carried by an organism.Phenotype – the way an organism looks and behaves.Alleles – genes that exists in alternative forms. The allele combination determines its genotype.

DominantRecessive

Punnet squares predict probabilities of outcomes.

Gametes produced by each parent pea plant

are shown along the top and left side.Remember: when the germ

cell that produces the sperm or egg divides, the

2n (diploid) number of chromosomes is split in

half: Tt becomes T and t.

T = dominantt = recessive

All life has heredity in All life has heredity in DNADNAPunnet squares predict

probabilities of outcomes.¼ of offspring are TT.½ of offspring are Tt.¼ of offspring are tt.

But ¾ of offspring are tall, and only ¼

are short (3:1 ratio).

T = dominantt = recessive

The dominant characteristic usuallyoverpowers the recessive one.The dominant characteristic usuallyoverpowers the recessive one.

Two pink-flowering plants are crossed. The offspring flower are as follows: 25% red, 25% white; 50% pink. What pattern of inheritance does flower color in these flowers follow?

A. dominanceB. multiple allelesC. incomplete dominanceD. recessivenessE. polygenic trait

All life has heredity in All life has heredity in DNADNAPedigree charts relate to

punnet squares 

Square = manCircle = womanFilled = diseaseHalf filled = carrierOpen = healthy

DNA and ProteinsDNA and ProteinsDNA and ProteinsDNA and Proteins

All organisms contain DNA.DNA (deoxyribonucleic acid) carries the genetic code for all organisms.Four nucleotides: Nitrogenous bases

A - adenineT – thymineG – guanineC - cytosine

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All life has heredity in All life has heredity in DNADNA

DNAThe code of life