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B. BIO/BIOCHEM MCAT > Genetics and evolution > Flashcards

Genetics and evolution Flashcards

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1
Q

Evolutionary fitness that includes both individual fitness (propagation of one’s own genes) and indirect fitness (cooperative behavior to help propagate genes of close relatives).

A

Inclusive fitness

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2
Q

A single common ancestor species diverges (or “radiates”) into several new species that fill different niches.

A

Adaptive radiation

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3
Q

Estimates time of divergence from a common ancestor based on differences between species. The more different two species are, the further back they diverged.

A

Molecular clock model

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4
Q

Chromosomal mutations

Deletion or duplication of an entire chromosome.
Results from nondisjunction during anaphase.

A

Aneuploidy

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5
Q

Chromosomal mutations

Deletion or duplication of many entire chromosomes.

A

Polyploidy

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6
Q

Chromosomal mutations

DNA segment gets reversed.
Can be caused by transposons.

A

Inversion

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7
Q

Chromosomal mutations

DNA segment gets substituted for a segment on a different chromosome.
Can be caused by transposons.

A

Translocation

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8
Q

Chromosomal mutations

DNA segment is missing.

A

Deletion

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9
Q

Chromosomal mutations

DNA segment is mistakenly copied multiple times.

A

Duplication

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10
Q

Chromosomal mutations

DNA segment inserted into a different chromosome.

A

Insertion

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11
Q

Gradualism vs punctuated equilibrium

Two theories of the rate of evolution.

A

Gradualism: evolution occurs at a constant and gradual rate.
Punctuated equilibrum: evolution occurs in rapid bursts followed by long periods of stability.

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12
Q

Theory that evolutionary fitness includes close relatives as well as an individual’s own offspring.
Example: altruism.

A

Inclusive fitness

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13
Q

Occurs through crossing over in prophase I of meiosis. Two alleles that are further apart on a chromosome have increased chance of crossing over.

A

Genetic recombination

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14
Q

Principles of natural selection

Extreme phenotype is favored, pushing the population toward that phenotype.
Example: black bears getting larger during the Ice Age.

A

Directional selection

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15
Q

Principles of natural selection

Intermediate, non-extreme phenotype is favored.
Example: insects in the forest will adopt an intermediate shade of green to maximize camouflage.

A

Stabilizing selection

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16
Q

Principles of natural selection

Multiple extremes are favored, pushing the population to polarized (bimodal) extremes.
Example: In an area with black and white rocks, rabbits will tend to be either black or white rather than gray for camouflage.

A

Disruptive selection

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17
Q

Mendelian Laws

Each gene has two alleles, which segregate into individual gametes during anaphase I.

A

Law of segregation

18
Q

Mendelian Laws

Alleles of separate genes do not affect probability of inheritance for each other. Does not apply to linked alleles.

A

Law of independent assortment

19
Q

Nucleotide mutations

A single nucleotide base pair is altered.

A

Point mutations

20
Q

Nucleotide mutations

The 3-base reading frame is shifted. Effect is more dramatic.

A

Frameshift mutations

21
Q

Nucleotide mutations

Change in DNA sequence, but no change in the expressed amino acid.

A

Silent mutation

22
Q

Nucleotide mutations

A different amino acid is expressed.

A

Missense

23
Q

Nucleotide mutations

A stop codon is expressed instead of an amino acid.

A

Nonsense

24
Q

Nucleotide mutations

Causes a shift in the reading frame and affects all downstream amino acids.

A

Insertion or deletion

25
Q

Genetic concepts

Small number of individuals (“founders”) establish a new population → loss of genetic diversity

A

Founder effect

26
Q

Genetic concepts

When certain genes become more expressed due to chance rather than natural selection.
More prominent in small populations.

A

Genetic drift

27
Q

Genetic concepts

Penetrance vs expressivity

A

Penetrance: the likelihood a phenotype is expressed for a given genotype
- Example: if you get the ‘bald gene’, how likely it is that you’ll actually go bald.
Expressivity: how intensely a phenotype is expressed for a given genotype.
- Example: if you get the ‘tall gene’, how tall you actually grow.

28
Q

Genetic concepts

Variation in how intensely a phenotype is expressed within a population of the same genotype.
Example: some lactose intolerant people can handle a small amount of dairy products, others can’t handle any.

A

Variable expressivity

29
Q

Genetic concepts

A major event that changes allele frequency in a segment of the population.
Example: founder effect.

A

Bottleneck event

30
Q

Types of genetic dominance

Dominant phenotype completely expressed.
Example: red rose + white rose = red rose offspring.

A

Complete dominance

31
Q

Types of genetic dominance

Recessive phenotype is partially expressed.
Example: red rose + white rose = pink rose offspring.

A

Incomplete dominance

32
Q

Types of genetic dominance

Both phenotypes are simultaneously expressed.
Example: red rose + white rose = children with half red petals and half white petals.

A

Codominance

33
Q

changes in gene expression unrelated to the DNA sequence.

A

epigenetics

34
Q

Mechanisms of epigenetics

A

Common mechanisms of epigenetic modification are methylation of DNA sequences and acetylation of histones.

35
Q

An epigenetic phenomenon where one of the inherited chromosomes (either the maternal or the paternal one) gets inactivated.

A

Genomic imprinting

36
Q

Five conditions of Hardy-Weinberg

A

1) Large population
2) No natural selection
3) Random mating
4) No genetic drift
5) No migration

37
Q

Hardy-Weinberg equation and principle

A
38
Q

Found only in males. Shorter than other chromosomes.

A

Y chromosome

39
Q

The sex-determining gene.
Found on the Y chromosome and leads to male characteristics like development of testicles.

A

SRY gene

40
Q

Y chromosome may have a higher mutation rate due to

A

high rate of division during spermatogenesis.

41
Q

In females, during development of individual embryonic cells, one copy of the X-chromosome can be randomly inactivated. This can result in a

A

mosaic phenotype.

B. BIO/BIOCHEM MCAT (29 decks)

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