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MCAT bio > genetic inheritance and evolution > Flashcards

genetic inheritance and evolution Flashcards

1
Q

mendelian genetics

A

pea plant experiements to track phenotypic variation and established dominant and recessive traits

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2
Q

genotype

A

combination of genes responsible for phenotype

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3
Q

phenotype

A

physical manifestation of a genotype
- multiple genotypes can show same phenotype

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4
Q

gene

A

sequence of dna that codes for a given trait

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5
Q

allele

A

variations of a gene

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6
Q

homologues

A

copies of the same chromosome
- same set of genes but different alleles

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7
Q

locus

A

region of a chromosome where a gene resides

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8
Q

descriptions of alleles

A

dominant and recessive

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9
Q

dominant allele

A

1 copy is needed to show phenotype

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10
Q

recessive

A

2 copies needed to show phenotype

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11
Q

do loss of function mutations tend to be dominant or recessive

A

recessive

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12
Q

do gain of function mutations tend to be dominant or recessive

A

dominant

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13
Q

example of fatal gain of function disease

A

huntingtons

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14
Q

punnett square

A

common technique to illustrate genetic cross over where parental genomes are aligned on each axis, with 4 or more outcomes

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15
Q

homozygus

A

2 copies of the same allele

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16
Q

heterozygus

A

1 copy of 2 different alleles

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17
Q

hemizygous

A

one copy of an allele is present
- nondisjunction

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18
Q

test cross

A

an individual with a DOMINANT phenotype is crossed with an individual of the recessive phenotype , if the dominant is homozygous , the f1 generation wont have any of recessive phenotype

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19
Q

back crossing

A

hybrid cross with a parent organism to obtain offspring similar to parent

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20
Q

wild type

A

default genotype or phenotype
w+ means no mutation

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21
Q

w (experiment group)

A

has mutation

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22
Q

w+

A

does not have mutation // wild type

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23
Q

complete dominance

A

medelian genetics where one dominant phenotype is always expressed over recessive

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24
Q

codominance

A

2 dominant alleles are expressed at the same time

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25
Q

what kind of dominance does the ABO blood type exhibit

A

co dominance

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26
Q

incomplete dominance

A

heterozygote blend of phenotypes
a red and white flower make pink

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27
Q

penetrance

A

likelyhood that a carrier of a genotype will manifest the corresponding phenotype
- how often a mutation is phenotypically expressed

28
Q

what factors determine penetrance

A

gene expression and epigenetic modification

29
Q

expressivity

A

intensity or extent of variation in a phenotype

30
Q

example of expressivity of a mutation

A

severity of a disease

31
Q

dihybrid cross

A

punnette square for two traits

32
Q

distribution of a dihybrid cross for two traits that are both heterozygous

A

9:3:3:1

33
Q

law of independent assortment

A

there is no link of inheritance between alleles of different genes
- applies to genes on different chromosomes AND genes on the same chromosome at different loci

34
Q

why does law of independent assortment apply to genes on the same chromosome

A

because of crossing over at the chiasmata point

35
Q

when does corssing over occur

A

prophase 1 of meiosis

36
Q

recombination frequency

A

describes how often a single cross over event will occur between two genes on the same chromosome
- if recombination frequency is 50% then the genes in question obey law of independent assortment

37
Q

centrimorgan (cM)

A

linkage
recombination is a distance between genes and 1% is linkage

38
Q

pedigree analysis

A

individuals arranged in generations
circles are female and squares are male

39
Q

what kind of autosomal mutations like to skip generations

A

recessive

40
Q

T/F: dominant mutations can skip generations

A

false

41
Q

sex-linked inheritance

A

genes located on the x chromosome
- males much more suseptible because they only have 1 x
- can be dominant or recessive

42
Q

evolution requires

A
  1. variation in population
  2. mechanism for those variations to be reproduced
  3. envirnmental constraints that favor some variations over others
43
Q

differential reproduction

A

envirnmental conditions that allow favorable variations to be more readily reproduced

44
Q

natural selection

A

tendency of certain phenotypes to be favored for reproduction
- not same thing as evolution!

45
Q

fitness

A

chance of reproduction associated with phenotype compared to a baseline
- must be determined in terms of specific envirnmental constrains

46
Q

group selection

A

natural selection acted on level of group

47
Q

inclusive fitness

A

expanded evolutionary definition of fitness to account for individuals and their relatives that share same alleles

48
Q

altruistic behavior

A

it is advantagous for an individual to engage in altruistic behavior or even self sacrifice to ensure the survival of more copies of the gene

49
Q

gene pool

A

combined set of all genes and alleles in a population

50
Q

hardy-weinberg equillibrium criteria

A

model of stable gene pools
1. diploid individuals reproduce sexually
2. mating is random
3. population is large
4. alleles are randomly distributed by sex
5. no mutations occur
6. there is no migration into or out of the population

51
Q

hardy-weinberg eqn

A

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

52
Q

what do p^2 and q^2 represent

A

homozygous genotypes

53
Q

2pq

A

frequency of heterozygotes

54
Q

a population has a 9% homozygous recessive trait, what % have the homozygous dominant?

A

P + q =1
sqr (.09) = .3 so 1-.3 =.7 so .7^2 = 49%

55
Q

polygenic

A

many genes go into a phenotype
example: height

56
Q

stabilizing selection

A

the median phenotype is selected for

57
Q

disruptive selection

A

selection against the average phenotype, favors both extremes

58
Q

directional selection

A

1 extreme is favored

59
Q

genetic drift

A

role of chance in determining reproductive fitness

60
Q

evolutionary bottleneck

A

external event dramatically decreases population size in a way that is essentially random

61
Q

speciation

A

new species evolves from evolution

62
Q

species

A

a group that can reproduce together and produce fertile offspring

63
Q

prezygotic barriers

A

prevent speciation from occuring before the formation of a zygote
ecological niches
incompatible anatomy
temporal/seasonal mating differences
inability to fertalize after intercourse

64
Q

postzygotic barriers

A

after the formation of a zygote
nonviable zygote
hybrid breakdown

65
Q

hybrid breakdown

A

hybrid is fertile but not in second generation

66
Q

leakage

A

genes travel between species

MCAT bio (12 decks)

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