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THE MCAT BIO-8
GENETICS & EVOLUTION
| Question | Answer |
|---|---|
| What is characteristic of X-linked disorders? | males have dx but females are carriers --> do not pass to offspring |
| heterochromatin | condensed DNA |
| euchromatin | loose DNA |
| Lyon's hypothesis | One of the 2 X's in a female will be inactivated as a Barr body |
| A person with 2 barr bodies has ____ X chromosomes | 3 |
| Autosomal Dominant | -single copy -do not skip generations -equal numbers of affected females and males -father to son transmission is observed |
| What is fitness defined by? | REPRODUCTIVE SUCCESS |
| directional selection | selects for trait on one extreme |
| stabilizing selection | selects for moderate trait, against extremes |
| disruptive selection | selects for both extremes |
| Group selection | natural selection acting on the group, not the individual |
| Altruism | sacrifices fitness of individual for benefit of group |
| Evolutionary success | frequency of alleles of an individual increased |
| Species (3) | -be able to interbreed -be able to produce fertile, viable offspring -does this naturally |
| Are a horse and donkey same species? | NO --> mule offspring is sterile |
| Speciation | formation of a new species |
| polymorphism | different forms of alleles / traits |
| adaptation | genetic change in a population caused by natural selection |
| specialization | adaptation of traits to better fill a niche |
| Inbreeding increases frequency of __ and decreases ___. | homozygotes / heterozygotes |
| Why is inbreeding so bad? | increases frequency of homozy. recessive detrimental alleles |
| Bottleneck effect | severe reduction in population size (i.e. natural disaster) |
| genetic drift and when does the effect increase? | random change in allele frequencies --> genetic drift increases as population size decreases |
| T / F: Bottlenecks increase the effect of genetic drift? | TRUE |
| divergent evolution | same lineage, evolving apart to be more different |
| Divergent evolution produces ___ structures. | homologous |
| homologous structures | structures that are embryologically similar but have different functions (i.e. whale flipper and human arm) |
| parallel evolution | same lineage, evolving separately but using similar mechanisms |
| convergent evolution | genetically unrelated species acquire same biological trait |
| analogous structures | structures that do the same job but have different origins (i.e. bird wings and bee wings) |
| coevolution | two species reciprocally affect each other's evolution (prey and predator) |
| parasitism | one benefits, other harmed |
| commensalism | one benefits, other unaffected |
| mutualism | both species benefit |
| ontogeny vs. phylogeny | -development through life of an organism -development through history of lineages as they change through time |
| Ontogeny Recapitulates Phylogeny Theory | This phrase suggests that an organism’s development will take it through each of the adult stages of its evolutionary history, or its phylogeny |
| Molecular Clock Theory | -measure of evolutionary change over time at molecular level -specific DNA seq / px spontaneously mutate at constant rates -that rate can be used to estimate how long ago 2 organisms diverged from common ancestor |
| What are neutral mutation? | random genetic drift mutations that are not acted on by natural selection |
| What is Oparin and Haldane's theory on origin of life? | organic molecules created by atmospheric gases zapped by lightening --> fall into ocean to make primordial soup (C,H,N,O) |
| What experiment confirmed origin of life theory? | Urey-Miller |
| RNA World Hypothesis | RNA is precursor to current life because RNA can store genetic info and catalyze chemical rxns |
| protocells | aggregates of RNA and px inside lipid envelopes |
| How did eukaryotes evolve? | -endosymbiosis --> big cx engulfed a smaller cx |
| What are 2 types of endosymbiosis? | -heterotrophs engulf mito -autotrophs engulf chloroplasts |
| How did prokaryotes evolve? stages | anaerobic heterotrophs --> anaerobic autotrophs --> aerobics |
| What is a chordate? | one of the phylums in the kingdom Animalia |
| What are features of a chordate? | notochord, gill slits in embryo (pharyngeal pouches, branchial arches), dorsal nerve cord |
| What is a vertebrate vs. chordate? | vertebrates are a subphylum of chordates |
| Chordates vs. vertebrates | -all chordates have a notochord, dorsally located nerve -all vertebrates have a backbone |
| Are all vertebrates chordates? Are all chordates vertebrates? | YES / NO |
| Notochord | rigid rod present at some stage of development in all chordates |
| p + q = | 1 |
| Hardy Weinberg equation | p^2 + 2pq + q^2 = 1 |
| 5 assumptions of Hardy-Weinberg | -large population (no genetic drift) -no mutation -no migration -random mating (no sexual selection) -all genes are equally successful at reproducing |
| What is a back-cross? | mating btwn offspring and parent |
| What is a test-cross? | Situation when you have a dominant phenotype (Aa or AA) --> cross with homozygous recessive aa |
| locus | location of a gene on a chromosome |
| allele | variant of a gene |
| Where do all alleles of the same gene exist? | same locus |
| How many alleles does each gene hold? | 2 - one from mom, one from dad |
| leakage | gene flow from one species to another --> concern for antibiotic resistance |
| gene pool | all of the alleles in a population |
| penetrance | frequency genotype will result in phenotype (whether you have it or not) |
| expressivity | to what degree a penetrant gene is expressed |
| When does tetrad formation occur? | meiosis I |
| In meiosis, are the daughter cells identical to parent cell? | NO |
| What does meiosis produce? | haploid (n) daughter cells |
| the law of _______( segregation or independent assortment) is dependent on the random arrangement of homologous chromosomes at the metaphase plate during Meiosis I. | independent assortment --> sometimes mom's chromo is on left, sometimes it's on rightW |
| The law of_____ ( segregation or independent assortment) is dependent on the separation of members of homologous pairs. | segregation |
| What is the site of crossing-over called? When does chiasma occur? | chiasma / tetrad formation |
| What lines up during meiosis I? Mitosis? | homologous chromosomes / sister chromatids |
| How many recombinants does a single crossover create? | 2 / 4 |
| Where are all of the sex-linked alleles located? | x chromosome |
| cytoplasmic inheritance | inheritance of things other than genomic DNA --> all cellular organelles such as mito are inherited from mother |
| mitochondria inheritance is from? | mother |
| inversion mutation | stretch of DNA breaks off and reattaches in opposite orientation |
| addition / insertion mutation | extra base is added to DNA sequence |
| What to addition / deletion mutations create? | frameshift mutation |
| translocation mutation | stretch of DNA breaks off and reattaches somewhere else |
| inborn errors of metabolism | genetic dx resulting in faulty metabolism --> PKA where ppl can't metabolize Phe |
| Are all mutagens carcinogens? Are all carcinogens mutagens? | NO / MOSTLY YES |
| some cancer can be mitogens, what is a mitogen? | increase mitosis |
| carcinogen vs. mutagen | -mutagen = causes mutation -carcinogen = causes mutation that causes cancer |
| vestigial structures | remnants of organs that have lost ancestral fxns |
| Do species, individuals, or populations evolve? | populations |
| Does chordate mean having a backbone? | NO --> bilateral symmetry |
| All vertebrates belong to what phylum? | chordata |
| r-selection | produce large number of offspring that mature rapidly with littler or no parental care |
| k-selection | small brood size with slow maturing offspring and strong parental care |
| adaptive radiation | single ancestral species gives rise to a number of different species |
| What carries out long-term evolutionary changes? | natural selection |
| coacervates | colloidal droplets made of polypeptides, nucleic acids, polysaccharides --> first cx thought to evolved from this cx type |
| prezygotic isolating mechanisms vs. postzygotic | -prevent zygote formation completely -offspring are inviable |
| inclusive fitness | number of alleles organism passes on to next generation |
| What ultimately creates evolution? | changing gene frequency |
| How to calculate the number of possible gametes for AaBbCc? | 2^n (n =3) |
| Why does inbreeding reduce fitness? | increase incidence of expression of deleterious recessive traits |
| What organisms fall under eukaryotes? | animls, plants, fungi, protozoans |
| Which organisms fall under prokaryotes? | bacteria (kingdom monera) |
| What are simplest eukaryotes? | protists |
| Some characteristics of x-linked recessive dx? | -more common in males -skip generations -NO father-son transmission |
| What does the Hardy-weinberg equilibrium oppose? | intro of new alleles into a population |
| Gram positive appear ___ after staining. Gram negative appear ____. | blue / pink |
| Where do sperm undergo maturation? What is that analogous to in a female? | epididymis / ovary |
| Characteristics of yeast cells | membrane-bound organelles, chitin wall |
| What is the smallest and achiral a.a.? | glycine |
| What is the imino acid? | proline --> helix breaker |
| What a.a. can form disulfide bonds? | cysteine |
| Background extinction vs. mass extinction | -background = steady loss -mass = abrupt loss |
| Founder effect | entire population gene pool is based on genes of individuals that founded population |
| What is estrogen synthesized from? | testosterone |
| Generation time | avg. amount of time btwn appearances of 2 successive generations (i.e. parent and offspring) |
| What does LH bind to in males? | leydig cells --> stimulate testosterone release --> FSH |
| all bacteria require ____ for growth and reproduction | carbon |
| autotrophic bacteria | bacteria that get carbon from CO2 |
| heterotrophic bacteria | bacteria that derive carbon from organic nutrients like sugar |
| cyanobacteria | use sunlight to produce sugars from CO2 |
| What eukaryotic organelles are derived from endosymbiotic bacteria? | mito and chloroplasts |
| Rank severity of damage: nonsense, silent, missense | nonsense > missense > silent |
| Where is rRNA produced? | nucleolus |
| What is the largest organelle in the cell? | nucleus |
| How many sets of tumor suppressor genes does each person have? | 1 |
| Human diet consist mostly of what type of sugar? | sucrose = glucose + fructose |
| Do erythrocytes have organelles? | NO |
| Where do erythrocytes get ATP? | cytoplasm and cx membrane supplies erythrocytes |
| population | group of interbreeding individuals of same species isolated from similar groups of same species |
| fundamental niche | potential conditions under which an organism can survive |
| realized niche | conditions individuals actually use to survive |
| Are analogous structure evolutionary related? | NO |
| Type A blood makes antibodies against? | Type B blood |
| When a population undergoes bottleneck, what is genotype of population? | homozygous |
| High degree of phenotypic plasticity? | environmental factors influence phenotype |
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