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Kaplan Biology > Ch. 12: Genetics and Evolution > Flashcards

Ch. 12: Genetics and Evolution Flashcards

1
Q

what are genes

A

genetic sequences that code for heritable traits which can be passed from one generation to the next

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2
Q

how are genes organized

A

into chromosomes

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3
Q

what are alleles

A

alternative forms of genes

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4
Q

what are homologues

A

the two copies of each chromosome each cell possesses

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5
Q

what is a locus

A

the specific area on a chromosome where a gene/gene info is located

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6
Q

what is a homizygous genotype

A

situation i which only one allele is present for a given gene

ex: parts of the x chromosome in males

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7
Q

what occurs during complete dominance

A

phenotype of one dominant allele masks the phenotype of a recessive allele

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8
Q

what occurs during codominance

A

phenotype two dominant alleles are expressed simultaneously

ex: AB bloodtype

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9
Q

what occurs during incomplete dominance

A

phenotype is an intermediate of the two homozygous phenotypes

ex: red snapdragons = RR, pink snapdragons = Rr, white snapdragons = rr

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10
Q

what is penetrance

A

proportion of a population with a genotype who actually express the phenotype

probability of expressing phenotype if you have the genotype

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11
Q

what is expressivity

A

different phenotypic manifestations across a population with the same genotype

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12
Q

what does the law of independent assortment specify

A

inheritance of one gene does not affect another

mendelian law, complicated by discovery of linked genes

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13
Q

what is the gene pool

A

all of the alleles that exist within a species

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14
Q

how does mutation to a DNA sequence affect alleles

A

can potential result in mutant alleles

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15
Q

what is a mutagen

A

substance that can cause a mutation

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16
Q

how many nucleotides are affected in point shift mutations

A

one nucleotide

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17
Q

where do silent mutations usually occur

A

the wobble position (last nucleotide in a codon)

results in no effect on the final synthesized protein

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18
Q

how is the final synthesized protein affected with a missense mutation

A

appropriate amino acid is switched for another

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19
Q

how is the final synthesized protein affect with a nonsense mutation

A

appropriate amino acid chain is stopped short by AUG (methionine)

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20
Q

how is the final synthesized protein affect with a frameshift mutation

A

appropriate amino acid chain has inserted or deleted sequence due to shift in reading frame

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21
Q

how are chromosomal mutations different than point shift mutations

A

large areas of the chromosome are affected

22
Q

what are deletion mutations

A

a large segment of DNA is lost from the chromosome

23
Q

what are duplication mutations

A

a segment of DNA is copied multiple times in the chromosome

24
Q

what are inversion mutations

A

a segment of DNA is reversed within the chromosome

25
Q

what are insertion mutations

A

a segment of DNA is moved from one chromosome to another

26
Q

what are translocation mutations

A

segment of DNA on one chromosome is swapped with that of another chromosome

27
Q

how are genes affected by genetic leakage

A

genes flow from one species to another during inter-species mating

28
Q

how is the gene pool affected by genetic drift

A

the composition of the gene pool changes due to chance, usually within isolated/small populations

29
Q

what occurs during the founder effect

A

a small population of a species becomes physically isolated from the rest d/t changes in the natural environment, resulting in genetic drift of the gene pool

30
Q

what occurs during bottlenecking

A

the amount of available breeders within a population are suddenly and drastically reduced

31
Q

what gene pool changes result in inbreeding depression

A

limited genetic variation resulting in reduced fitness of the population

32
Q

what gene pool changes result from outbreeding/outcrossing

A

introduction of unrelated individuals to a breeding pool, possibly increasing population fitness

33
Q

how many traits are studied in a monohybrid cross

A

one trait

34
Q

what individuals in a genetic cross are the P generation

A

the parents, the ones being crossed

35
Q

what individuals in a genetic cross are the F generation

A

the offspring/filla, the ones being produced

36
Q

when crossing two heterozygotes of a completely dominant trait, what are the genotypic and phenotypic ratios of the offspring?

A

Rr x Rr
genotype - 1:2:1 RR x Rr X rr
phenotype - 3:1 RR and Rr x rr

37
Q

what is the phenotypic ratios of offspring for a heterozygous dihybrid cross

A

TtPp x TtPp

phenotype: 9:3:3:1

38
Q

on what chromosome are sex-linked traits carried

A

seX-linked = X linked, recessive

can occur on Y but very, very rare

39
Q

what is a chiasma

A

cross over of genes on homologous chromosomes, more likely with genes further apart on a chromosome

40
Q

what does recombination frequency measure

A

likelihood that two alleles are separated from each other during crossover

41
Q

what does a genetic map plot

A

the relative distance between genes on chromosomes

42
Q

what are centimorgans

A

map units, the distance that corresponded to a 1% increased chance of recombination between two genes

25 map units apart = 25% chance of recombination

43
Q

what is the hardy-weinberg equation

A

p + q = 1 where p is frequency of dominant allele and q is frequency of the recessive allele

therefore…

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

44
Q

what do the criteria for the Hardy-Weinberg principle all imply

A

study population is NOT undergoing evolution; allele frequency will remain stable over time

45
Q

what does the theory of natural selection imply about a species

A

certain characteristics/traits of individuals within a species may help those individuals have greater reproductive successes which increases the likelihood of those genes being passed on to offspring

46
Q

how does stabilizing selection impact phenotypes

A

selection against extremes keeps phenotypes within a certain range

47
Q

how does directional selection impact phenotypes

A

adaptive pressure shifts phenotype towards an extreme

48
Q

how does disruptive selection impact phenotypes

A

selection of two extreme phenotypes over the norm

49
Q

what is the effect of adaptive radiation

A

rapid rise of a number of different species, each with their own niche, from a common ancestor

50
Q

what is the definition of species

A

the largest group of organisms capable of breeding to form fertile offspring

51
Q

what is accomplished through speciation

A

a new species is formed

Kaplan Biology (9 decks)

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