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Kaplan MCAT > BIO Ch. 12 Genetics and Evolution > Flashcards

BIO Ch. 12 Genetics and Evolution Flashcards

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MCAT flashcards
1
Q

What makes blood type O the universal donor?

A

it has neither A or B antigen, but both A and B antibodies

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2
Q

What makes blood type AB the universal recipient?

A

it has both A and B antigens but no antibodies

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3
Q

What is the diff b/w A and B blood types?

A

blood type A carries A antigen in their erythrocytes and has circulating anti-B antibodies
blood type B carries B antigen in their erythrocytes and has circulating anti-A antibodies

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4
Q

What is recessive and dominant?

A

if only 1 copy of an allele is needed to express a given phenotype, the allele is said to be dominant
if 2 copies of an allele are required to express a given phenotype, the allele is said to be recessive

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5
Q

What is the diff b/w complete dominance and codominance?

A

complete dominance is when the presence of 1 dominant allele will mask the recessive alleles. codominance is when both dominant alleles are expressed, and neither is dominant over the other

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6
Q

What is penetrance?

A

The proportion of individuals with a given genotype who express the phenotype

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7
Q

What is expressivity?

A

the different manifestations of the same genotype across the population

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8
Q

What provides for great genetic diversity in the offspring?

A

segregation and independent assortment

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9
Q

What are the 3 ways bacteria increase genetic variability?

A

transformation, conjugation and transuction

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10
Q

What are the differences between a mutant and a wild-type allele?

A

wild-type are normal or natural alleles, mutant is an allele that has been mutated at the DNA level

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11
Q

How does a point mutation occur?

A

when 1 nucleotide in DNA (A, C, T, or G) is swapped for another

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12
Q

What are the 3 types of point mutation?

A

silent, missense, and nonsense

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13
Q

How does a silent mutation occur?

A

when the change in nucleotide does not affect the final protein synergized from the gene usually do to degeneracy (wobble position)

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14
Q

How does a missense mutation occur?

A

when the change in nucleotide results in substituting 1 AA for another in the final protein

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15
Q

How does a nonsense mutation occur?

A

when the change in nucleotide results in substituting a stop codon for AA in the final protein

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16
Q

How does a frameshift mutation occur?

A

when nucleotides are inserted into or deleted from the genome, leading to a shift in the reading frame. 2 types of frameshift are insertion and deletion

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17
Q

How does a chromosomal mutation occur?

A

large-scale mutation in which large segments of DNA are affected by translocation, insertion, and deletion

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18
Q

How does a deletion mutation occur?

A

when a large segment of DNA is lost from the chromosome
small deletions are considered frameshift mutations

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19
Q

How does a duplication mutation occur?

A

when a segment of DNA is copied multiple times in a genome

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20
Q

How does an inversion mutation occur?

A

when a segment of DNA is reversed within the chromosome

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21
Q

How does an insertion mutation occur?

A

when a segment of DNA is moved from one chromosome to another
small insertion mutations are considered frameshift

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22
Q

What is an advantageous mutation?

A

mutation that confers a positive selective advantage that may allow the organism to produce more offspring

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22
Q

How does a translocation mutation occur?

A

when a segment of DNA from one chromosome is swapped with a segment of DNA from another chromosome

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23
Q

What is an example of an advantageous mutation?

A

sickle cell allows for a natural resistance to malaria as the blood cells have a short enough lifespan that the parasite that causes malaria cannot reproduce

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24
Q

What is deleterious mutation?

A

mutations that are detrimental

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25
Q

What is an example of deleterious mutation?

A

xeroderma pigmentosum (XP) patients lack the repair mechanism for DNA damage and, thus experience frequent diagnosis of malignancy especially of the skin

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26
Q

What are inborn errors of metabolism?

A

a deleterious mutation of genes required for metabolism

27
Q

What is an example of an inborn error of metabolism??

A

in phenylketonuria (PKU), the enzyme phenylalanine hydrolase which completes the metabolism of phenylalanine accumulates, causing seizes, impaired cerebral functions, learning disabilities, and musty body odor

28
Q

What is leakage?

A

a flow of genes from different species
ex: a male forse mating with a female donkey

29
Q

Why can’t hybrid species reproduce?

A

because they have an odd number of chromosomes

30
Q

What is genetic drift?

A

a change in the composition of the gene pool due to chance

31
Q

What is the founder effect?

A

an extreme case of genetic drift in which a small population of species finds itself in reproductive isolation from other populations due to natural barriers or catastrophic events or bottlenecks that drastically reduce the size of the population available for breeding

32
Q

What does Mendel’s Second Law of Independent Assortment state?

A

the inheritance of one gene is independent of other genes. aligns more with prophase I of meiosis

33
Q

What are the 3 things that cause a reduction in genetic diversity?

A

genetic drift, the founder effect, and inbreeding

34
Q

What is the phenotypic and genotypic ratio of crossing 2 heterozygous parents for a trait with complete dominance?

A

F2 generation is 1:2:1 for genotype, and 3:1 for phenotype

35
Q

What is the phenotypic and genotypic ratio of crossing 2 homozygous parents?

A

F1 phenotypic and genotypic ratios are both 100%

36
Q

When is a test/back cross used?

A

to deterine the unkown genotype?

37
Q

What is the unknown genotype of a test cross if all the offspring are dominant phenotype?

A

the unknown genotype is homozygous dominant

38
Q

What is the unknown genotype of a test cross if there is a 1:1 distribution to recessive phenotype?

A

the unknown genotype is heterzyogous

39
Q

What is the phenotypic ratio of dihybrid crossing 2 heterozygous for a trait with complete dominance?

A

9:3:3:1

40
Q

What is the diff b/w female and male chromosomes?

A

females have XX chromosomes and can be heterozygous or homozygous
males have XY, thus are hemizygous

41
Q

What is an example of a sex-linked trait?

A

hemophilia
sex-linked traits are X-linked recessive

42
Q

What is chiasma?

A

the statement that the further apart 2 genes are, the more likely there will be a point of crossing over

43
Q

What is recommendation frequency?

A

the likelihood that 2 alleles are separated from each other during crossing over in meiosis

44
Q

What is the diff in recombination frequency b/w tightly and weakly linked genes?

A

tightly linked have a recommendation frequency sloe to 0%, while weakly are approaching 50%

45
Q

What are the criteria of the Hary-Weinberg equilibrium principle for evolution not to occur?

A
  1. The population is large - no genetic drift
  2. no mutation affecting the gene pool
  3. mating is random - no sexual selection
  4. no migration in or out of the population
  5. genes in the population are equally successful in reproducing
46
Q

What is the use of the Hardy-Weinberg equilibrium principle?

A

to predict allelic, genotypic, and phenotypic frequency, and demonstrate that evolution is not occurring in a population

47
Q

What is the Hardy-Weinberg equilibrium principle?

A

(p + q)^2 = 1 –> alleles in the populaiton
p^2 +2pq + q^2 = 1 –> frequency of geno and phenotypes

p = frequency of dominant allele
q = frequency of recessive allele
p^2 = frequency of homozygous dominant genotype
2pq = frequency of homozygous recessive genotype

48
Q

What is fitness?

A

the level of reproductive success

49
Q

What is natural selection equal to?

A

survival of the fittest

50
Q

What do p^2 + 2pq and q^2 represent?

A

The sum of p^2 + 2pq represents the frequency of the dominant phenotype, and q^2 presents the frequency of the recessive phenotypes

51
Q

What is the Differential Reproduction

A

an evolutionary theory that states that favorable mutations or recommendations are more likely to be passed on to the next generation, and over time, this mutation will be found more often throughout the population. The opposite can happen where individuals with unfavorable traits do not reach reproductive maturity, and these traits are not passed down through generations

52
Q

What does Mendel’s First Law of segregation state?

A

an organism has 2 alleles for each gene, which segregate during meiosis, resulting in gametes carrying one 1 allele for a trait. aligns more with anaphase I of meiosis

53
Q

What did the Griffith experiment demonstrate?

A

the transforming principle, converting non-virulent bacteria into virulent bacteria by exposure to heat-killed virulent bacteria

54
Q

What did the Avery-MacLeod-McCarty experiment demonstrate?

A

that DNA is the genetic material because degradation of DNA leads to a cessation of bacterial transformation

55
Q

What did the Hershey-chase experiment demonstrate?

A

confirmed that DNA is the genetic material because only radiolabeled DNA could be found in bacteriophage-infected bacteria

56
Q

What is the modern synthesis model/neo-Darwinism?

A

accounts for mutations and recombination as mechanisms of variation and considers differential reproduction to be the mechanism of reproductive success

57
Q

What is Inclusive Fitness?

A

a measure of an organism’s success by the number of offsprings, and its ability to support the offspring, and the offsprings ability to support others

58
Q

What is the role of Stabilizing selection?

A

acts to maintain phenotypes within a tight range, eliminating those of the extremes

59
Q

How is Direction Selection caused?

A

caused by adaptive pressure that leads to the dominant extreme phenotype

60
Q

What happens in disruptive selection?

A

the 2 extreme phenotypes are accepted over the norm

61
Q

What is the diff b/w prezygotic and postzygotic?

A

Prezygotic - Do not allow the formation of a zygote due to biological and behavioral differences between the 2 species
Postzygotic - allows for the formation of a zygote but leads to non-viable or sterile offspring

62
Q

What is adapative radiaiton?

A

the rapid emergence of multiple species from a common ancestor, each of which occupies its ecological niche

63
Q

What is divergent evolution?

A

occurs when 2 species sharing a common ancestor become more different due to evolutionary pressures

64
Q

What is the difference b/w parallel and convergent evolution?

A

parallel - occurs when 2 species share a common ancestor and evolve in similar ways due to analogous selection pressures
convergent - occurs when 2 species not sharing a common ancestor evolve in similar ways due to analogous selection pressures

65
Q

What is punctuated equilibrium?

A

states that for some species, little evolution occurs for a long period, which is interrupted by a rapid burst of evolutionary change

66
Q

What is the diff b/w stabilizing, directional, and disruptive patterns of selection?

A

stabilizing - loss of extremes, maintenance of phenotype in a small window
directional - moves the average phenotypes toward one extreme
disruptive - moves phenotype toward both extremes with a loss of the norm; specification may occur

Kaplan MCAT (52 decks)

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