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Genetics exam #3 > Population Genetics > Flashcards

Population Genetics Flashcards

0
Q

“nothing in biology makes sense except in the light of evolution”

A

Theodosius Dobzhansky

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1
Q

a geneticist codified the definition of evolution as genetics and the origin of species

A

thomas hunt morgan’s pupil

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2
Q

study of genetic variation within species

A

pop genetics

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3
Q

group of freely interbreeding individuals

  • composed of local populations (Demes)
  • sexually reproducing
A

population

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4
Q

all alleles of every gene in pop

A

gene pool

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5
Q

Mendel focused on observable traits

A

polymorphism

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6
Q

variation in the genetic code of a pop

  • > 1 allele
  • SNPs (smallest unit of genetic polymorphism)
  • 90% of genetic variation in humans
A

genetic polymorphism

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7
Q

no variation

A

monomorphism

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8
Q

change in a single base pair

A

point mutation

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9
Q

don’t alter RNA or polypeptides

A

silent mutations

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10
Q

alter polypeptides

A

missense mutation

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11
Q

change codon to stop codon

A

nonsense mutation

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12
Q

change translation reading frame

A

frameshift mutations

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13
Q

“random” chance (genetic drift)

-selection

A

ultimate: causes of genetic variation

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14
Q

proximate-causes of genetic variation

A

mutations

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15
Q

american scientists mainly discounted selection

-english scientists found several examples of power of selection

A

atlantic drift

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16
Q

early geneticists were trying to disprove darwin’s theory of evolution via natural selection

A

neutral pop genetics

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17
Q

proportion of gene pool that is a particular allele

A

allele freq.

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18
Q

-proportion of individuals in a pop with a particular genotype

A

genotype freq.

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19
Q

hardy-weinberg equation

A

p^2 + 2pq + q^2 =1

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20
Q 
p=
q=
p^2=
q^2=
2pq=
A 
freq of an allele
freq of other allele
freq of homozygotes for first allele
freq of homozygotes for second allele
freq of heterozygotes
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21
Q

when allele and genotype freq match expectations, pop is not changing
-evolutionary stasis

A

hardy weinberg equilibrium

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22
Q

semi-random generation of NEW alleles

-neutral, beneficial, or deleterious

A

mutation

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23
Q

mechanisms altering existing genetic variation

A

genetic drift
migration
selection
non-random mating

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24
Q

___________ _________ more likely than beneficial mutations

A

deleterious mutations

25
Q

number of new mutations per generation per gene or DNA segment

A

mutation rate

26
Q

random fluctuations in allele freq.

  • no selection
  • random mating
A

genetic drift

27
Q

discovery of genetic drift

A

seawall wright

28
Q

typically leads to loss of allele 0% or allele fixation 100%

A

genetic drift

29
Q

genetic drift is affected by

A

pop size
initial allele freq
# generations

30
Q

probability that a new mutation will be fixed

A 
1/2N= probability of fixation= initial freq
N= pop size
31
Q

if fixation of new allele does occur, how long does it take?

assumptions?

A

4N generations on average

-constant pop size, no selection, random mating

32
Q

genetic drift can lead to the fixation of ______,______, or ________ alleles

A

deleterious, neutral, or beneficial

33
Q

population ___________
-contraction of a pop
-genetic drift becomes a strong force
“tears of the cheetah” 10-12,000 years ago, a ________ wiped out most genetic diversity

A

bottleneck

34
Q

small # of individuals colonize new area

-envision the colonization of deserted island

A

founder effect

35
Q

migration between populations promotes

A

higher genetic diversity

36
Q

due to migrants that successfully breed and alleles are successfully propagated
-tends to homogenize allele freq

A

gene flow

37
Q

all freq can be used to estimate ________ _____

A

migration rates

38
Q

________ affects allele freq

-affects the fitness conferred by alleles and genotypes

A

selection

39
Q

the likelihood that a genotype will contribute to the gene pool of the next generation

A

fitness

40
Q

selections acts on both new and existing _________ _______

A

genetic variation

41
Q

our world is constantly changing, thus …

A

the effects of selection vary through time

42
Q

alleles and genotypes that confer higher fitness can ________
alleles and genotypes that are deleterious _______

A

increase

decrease

43
Q

fittest genotype, aa has fitness value of 1

  • Aa, on avg contributes 20% _____ offspring to the next generation
  • AA contributes 90% _____ offspring
A 
darwinian fitness (W)
fewer
44
Q

favors traits at one extreme of phenotypic distribution

-can drive fixation

A

directional selection

45
Q

under directional selection, the freq of the selected allele ________ over several generations

A

increases

46
Q
  • intermediate phenotypes are the most fit

- tends to decrease genetic diversity

A

stabilizing selection

47
Q

traits at 2 or more extremes of phenotypic space are most fit

A

disruptive selection

48
Q

when divergent phenotypes or alleles are equally fit in a homozygous environment
-heterozygote advantage (sickle cell disease)

A

balancing selection

49
Q

neg freq dependent selection

-fitness decreases as allele or phenotype freq increases

A

balancing selection

50
Q

positive (similar phenotypes mate more freq)

neg (opposites attract)

A

assortative mating

51
Q

mating btween closely related individuals

-decreases genetic diversity

A

inbredding

52
Q

mating btween unrelated individuals

A

outbreeding

53
Q

exon shuffling, horizontal gene transfer, gene introgression, species hybrids

A

sources of genetic variation

54
Q

results in novel genes and proteins

A

exon shuffling

55
Q

several causes of exon shuffling..

A 
double crossovers
duplications
transposable elements (jumping genes)
56
Q

transposable elements

  • DNA seq that changes position in the _________
  • can make up ______ _______ of genome
A

genome

large portion

57
Q

organism incorporates genetic material of another that is not the parent
20-30% of prok genetic variation

A

horizontal gene transfer

58
Q

gene flow btween species

-multiple step process: 1,2,3

A

genetic introgression

  1. produce viable hybrids
  2. hybrids backcross (reproduction with non hybrids)
  3. backcrossing continues
59
Q

__________ btween two species can create new species if they are in euk, most typical plants

A

hybridization

Genetics exam #3 (8 decks)

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