Protein Synthesis (transcription and translation), Genetics, and Evolution

CBA Review

DNA vs. RNA

DNA RNA1.Double stranded2.Deoxyribose sugar3.Guanine, cytosine,

adenine, thymine4.(G-C), (A-T)5.Stays in nucleus

1.Single-stranded2.Ribose sugar3.Guanine, cytosine,

adenine, uracil4.(G-C), (A-U)5.mRNA moves from

nucleus to cytoplasm, tRNA and rRNA (ribosomes) stay in cytoplsam.

TRANSCRIPTION!mRNA…

copies DNA in nucleustakes copied gene to cytoplasmAttaches to RIBOSOME (rRNA)Made up of three letter triplets called

CODONS

DNA Strand:AGG-GAC-TAT-GAT-AGC

Complimentary RNA Strand:UCC-CUG-AUA-CUA-UCG

TRANSLATION!tRNA…

Reads the mRNA each CODON at a timeHas the opposite of the codon, called the

ANTI-CODON, which matches using base-pairing rules (A-U), (G-C)

Translation happens in the CYTOPLASM within RIBOSOMES.

tRNA ANTI-CODONtRNA ANTI-CODON

Amino AcidsMonomers of proteinsEvery codon codes for an amino acidDNA Strand:

ATA-CGG-ACC-TAA-GAG

mRNA Strand:Write on white board

Amino Acid Sequence:Write on white board

GENETICS! Gene Regulation Mendelian Genetics

Principle of Dominance Monohybrid and dihybrid crosses

Non-Mendelian Genetics Incomplete Dominance Codominance Polygenic Traits X-Linked Traits

Gene Technology Recombinant DNA DNA Fingerprinting Karyotyping

Pedigrees Chromosomal Mutations Meiosis

Gene RegulationRemember Oxana Malaya, the girl who was

raised by dogsWhen she was born, she was completely

normal, mentally and physicallyShe now experiences difficulties learning and

with language and lives in assisted living. Why?

Gene RegulationThe environment influences gene

expression.Genes:

Expressed = transcription CAN happenNot expressed = transcription CANNOT

happenProkaryotes (Bacteria)

LAC Operon – set of genes that make the enzymes that digest lactoseNo lactose present: genes NOT expressed (Turned

“off”) Lactose present: genes EXPRESSED (turned “on”

Gene RegulationEukaryotes:

Use transcription factorsMore complex process than in prokaryotesEpigenome: the “marker” proteins that turn

genes on and off

Mendelian GeneticsMonohybrid Crosses:

Letters on the sides of the Punnett square are GAMETES (Law of Segregation)

Dihybrid Crosses: RrYy x RrYyWill always end up with a 9:3:3:1 phenotypic

ratioFOIL to find gametes (Law of Independent

Assortment)

Non-Mendelian GeneticsIncomplete Dominance: heterogygotes

have “blended” appearance (If RR = Red, and WW = White, then RW = Pink)

Codominance: BOTH traits are expressed equally in heterozygotes (COWdominance: if BB = black cow and WW = white cow, then BW = black and white spotted cow)

Non-Mendelian Genetics (cont.)X-Linked Traits:

Carried on the X-ChromosomeFemales are XX, males are XY, so males

CANNOT be heterozygous for X-linked traitsPolygenic Traits:

More than one set of alleles for the traitYou see a bell-curve distribution of

phenotypes with these traitsEx- hair color, height, skin tone, etc

Gene TechnologyRecombinant DNA: genes inserted into

PLASMIDS of bacteria to “trick” the bacteria into making the proteins that are desired

Ex: Insulin for people with diabetes

Gene TechnologyDNA fingerprinting:

Everyone has different DNA fingerprints EXCEPT IDENTICAL TWINS!

Used in paternity tests and crime scenes

Gene Technology Karyotyping:

Used to detect chromosomal abnormalitiesCan be performed while a woman is pregnant

to detect abnormalities in the fetus: amniocentesis

NON-DISJUNCTION mutations cause TRISOMIES! Trisomy 21: Down

Syndrome

Caused by NON-DISJUNCTION mutation

PedigreesDARKENED individuals are AFFECTEDIf you see half-colored circles or squares,

the individual is a CARRIERNot all carriers are half-colored.

Chromosomal Mutations

Meiosis VS Mitosis

Meiosis VS MitosisMeiosis: 2n 1n

Diploid cells to haploid cellsMakes GAMETES (eggs and sperm)

Mitosis: 2n 2nDiploid cells to diploid cells

Non-Disjunction MutationsCause a TRISOMY on a karyotypeChromosomes don’t separate during

meiosis

EvolutionEndosymbiotic TheoryOrigin of Complex MoleculesEvidence of Evolution

FossilsHomologous, Vestigial structuresEmbryologyDNA evidence

Mechanisms of EvolutionNatural selection, mutation, migration (gene flow),

genetic drift (bottlenecking, founder-effect) Directional, Disruptive, Stabilizing selectionConvergent vs Divergent Evolution

Endosymbiotic TheoryMirochondria and Chloroplasts used to be

bacteria!

Origin of Complex MoleculesOparin & Haldane hypothesized that amino

acids could form in the early Earth’s environment

Miller & Urey tested it…..and it worked!

AMINO ACIDS formed after a week!

Iron-Sulfur World HypothesisDiscovery of ecosystems based on

chemosynthesis in deep hydrothermal vents offered support

Chemosynthesis: making glucose using inorganic molecules instead of sunlight as a catalyst

Catalysts in this instance: Iron (Fe) and Sulfur (S)

RNA World HypothesisRNA came before DNA because

CATALYTIC RNA is SELF-REPLICATING.Catalytic RNA needs no proteins to aid in

the process of replication, unlike DNACatalytic RNA acts like an enzyme, but it is

notRNA = nucleic acid, enzymes = proteins

FossilsOlder fossils are in lower layersNewer fossils are in top layersWhen fossils disappear from one layer to another, the organisms must have gone extinct

Gradualism vs Punctuated Equilibrium

GradualismTRANSITION FOSSILS

Punctuated EquilibriumNO transition fossils

Punctuated Equilibrium

Homologous StructuresSimilar because of common ancestryDIVERGENT EVOLUTION

Analogous StructuresIndependent evolution—no common

ancestryCONVERGENT EVOLUTION

Vestigial StructuresNot used in modern species; evidence of

ancestryEx- leg bones in whales, appendix in

humans

Molecular EvidenceMore DNA in common = moreclosely relatedDNA similarities = Amino Acid similarities

EmbryologyAll vertebrates go through similar

embryonic stages early in developmentTails become backbones

Adaptive RadiationDivergent EvolutionAn ancestral

species diversifies into many different species

Ex- mammals after dinosaur extinction

Hardy-Weinberg EquilibriumWhen no evolution is happeningRandom matingNo environmental pressuresDoes not exist in real life

Convergent vs Divergent

CONVERGENT DIVERGENT

UNRELATED species adapt to similar environments

Produces ANALOGOUS sturctures

RELATED species become more different

Produces HOMOLOUS structures

Types of Natural Selection

Cladograms