Transcript CBA Review

CBA Review
Protein Synthesis (transcription and translation),
Genetics, and Evolution
DNA vs. RNA
DNA
1. Double stranded
2. Deoxyribose sugar
3. Guanine, cytosine, adenine,
thymine
4. (G-C), (A-T)
5. Stays in nucleus
RNA
1. Single-stranded
2. Ribose sugar
3. Guanine, cytosine, adenine,
uracil
4. (G-C), (A-U)
5. mRNA moves from nucleus to
cytoplasm, tRNA and rRNA
(ribosomes) stay in cytoplsam.
TRANSCRIPTION!
 mRNA…
 copies DNA in nucleus
 takes copied gene to cytoplasm
 Attaches 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 time
 Has 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-CODON
Amino Acids
 Monomers of proteins
 Every codon codes for an amino acid
 DNA 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 Regulation
 Remember Oxana Malaya, the girl who was raised by dogs
 When she was born, she was completely normal, mentally and
physically
 She now experiences difficulties learning and with language and
lives in assisted living. Why?
Gene Regulation
 The environment influences gene expression.
 Genes:
 Expressed = transcription CAN happen
 Not expressed = transcription CANNOT happen
 Prokaryotes (Bacteria)
 LAC Operon – set of genes that make the enzymes that digest
lactose
 No lactose present: genes NOT expressed (Turned “off ”)
 Lactose present: genes EXPRESSED (turned “on”
Gene Regulation
 Eukaryotes:
 Use transcription factors
 More complex process than in prokaryotes
 Epigenome: the “marker” proteins that turn genes on and off
Mendelian Genetics
 Monohybrid Crosses:
 Letters on the sides of the Punnett square are GAMETES (Law
of Segregation)
 Dihybrid Crosses:
 RrYy x RrYy
 Will always end up with a 9:3:3:1 phenotypic ratio
 FOIL to find gametes (Law of Independent Assortment)
Non-Mendelian Genetics
 Incomplete 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-Chromosome
 Females are XX, males are XY, so males CANNOT be
heterozygous for X-linked traits
 Polygenic Traits:
 More than one set of alleles for the trait
 You see a bell-curve distribution of phenotypes with these traits
 Ex- hair color, height, skin tone, etc
Gene Technology
 Recombinant 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 Technology
 DNA fingerprinting:
 Everyone has different DNA fingerprints EXCEPT
IDENTICAL TWINS!
 Used in paternity tests and crime scenes
Gene Technology
 Karyotyping:
 Used to detect chromosomal abnormalities
 Can 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 NONDISJUNCTION mutation
Pedigrees
 DARKENED individuals are AFFECTED
 If you see half-colored circles or squares, the individual is a
CARRIER
 Not all carriers are half-colored.
Chromosomal Mutations
Meiosis VS Mitosis
Meiosis VS Mitosis
 Meiosis: 2n  1n
 Diploid cells to haploid cells
 Makes GAMETES (eggs and sperm)
 Mitosis: 2n  2n
 Diploid cells to diploid cells
Non-Disjunction Mutations
 Cause a TRISOMY on a karyotype
 Chromosomes don’t separate during meiosis
Evolution
 Endosymbiotic Theory
 Origin of Complex Molecules
 Evidence of Evolution
 Fossils
 Homologous, Vestigial structures
 Embryology
 DNA evidence
 Mechanisms of Evolution
 Natural selection, mutation, migration (gene flow), genetic
drift (bottlenecking, founder-effect)
 Directional, Disruptive, Stabilizing selection
 Convergent vs Divergent Evolution
Endosymbiotic Theory
 Mirochondria and Chloroplasts used to be bacteria!
Origin of Complex Molecules
 Oparin & 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 Hypothesis
 Discovery 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 Hypothesis
 RNA came before DNA because CATALYTIC RNA is
SELF-REPLICATING.
 Catalytic RNA needs no proteins to aid in the process of
replication, unlike DNA
 Catalytic RNA acts like an enzyme, but it is not
 RNA = nucleic acid, enzymes = proteins
Fossils
 Older fossils are in lower layers
 Newer fossils are in top layers
 When fossils disappear from
one layer to another, the organisms
must have gone extinct
Gradualism vs Punctuated
Equilibrium
Gradualism
 TRANSITION FOSSILS
Punctuated Equilibrium
 NO transition fossils
Punctuated Equilibrium
Homologous Structures
 Similar because of common ancestry
 DIVERGENT EVOLUTION
Analogous Structures
 Independent evolution—no common ancestry
 CONVERGENT EVOLUTION
Vestigial Structures
 Not used in modern species; evidence of ancestry
 Ex- leg bones in whales, appendix in humans
Molecular Evidence
 More DNA in
common = more
closely related
 DNA similarities =
Amino Acid similarities
Embryology
 All vertebrates go through similar embryonic stages early in
development
 Tails become backbones
Adaptive Radiation
 Divergent Evolution
 An ancestral species
diversifies into many
different species
 Ex- mammals after
dinosaur extinction
Hardy-Weinberg Equilibrium
 When no evolution is happening
 Random mating
 No environmental pressures
 Does not exist in real life
Convergent vs Divergent
CONVERGENT
DIVERGENT
 UNRELATED species
 RELATED species become
adapt to similar
environments
 Produces ANALOGOUS
sturctures
more different
 Produces HOMOLOUS
structures
Types of Natural Selection
Cladograms