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BIO106 - Evolutionary Biology > Lesson 6: Mutation > Flashcards

Lesson 6: Mutation Flashcards

1
Q
  • genetic substrate for natural selection
  • raw material for evolution
A

mutation

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2
Q

What reduces variation?

A
  1. genetic drift in finite populations
  2. reduction in allelic diversity
  3. reduction in heterozygosity (inbreeding)
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3
Q

Sources of allelic variation

A

mutation

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4
Q

Sources of Genotypic Variation

A

Sex (meiosis)

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5
Q

heritable variation changes in gene expression without changes in genetic code

A

epigenetic inheritance

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6
Q

if there is no __ __, neither genetic drift nor natural selection would be able to change allelic frequencies, because there would be nothing to change

A

genetic variation

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7
Q

requires genetic variation upon which it could act

A

natural selection

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8
Q
  • change in genetic code
  • new alleles and/or new genes
A

mutations

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9
Q

Mutations: new alleles

A

nucleotide substitutions, insertions, deletions

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10
Q

Mutations: new genes

A
  • gene duplication or deletions
  • exon shuffling
  • horizontal gene transfer (not always considered mutation)
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11
Q

Types of Mutations

A
  1. chromosomal duplications or deletions
  2. deletions of large chromosomal regions
  3. chromosomal inversions
  4. whole genome duplication
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12
Q
  • no novel alleles
  • only novel genotypes
A

sex

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13
Q

Sex

A
  1. genetic recombination
  2. random mating
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14
Q

shuffling of combinations of alleles along a chromosome

A

genetic recombination

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15
Q

shuffling of combinations of haploid chromosomes into new genotypes

A

random mating

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16
Q

Types of Mutations:
AT THE NUCLEOTIDE LEVEL

A
  1. single nucleotide substitutions
  2. insertions
  3. deletion
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17
Q

mutation at the nucleotide level is also called…?

A

point mutations

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18
Q

types of single nucleotide substitutions

A
  1. transitions
  2. transversions
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19
Q

Types of Mutations:
AT THE “GENE” LEVEL

A
  1. gene insertions
  2. gene deletions
  3. exon shuffling
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20
Q

Types of gene insertions

A
  1. gene duplication
  2. transposons
  3. horizontal gene transfer
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21
Q

Types of gene deletions

A
  1. pseudogenization
  2. transposons
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22
Q

Types of Mutations:
AT THE CHROMOSOME LEVEL

A

chromosome
- duplications
- deletions
- inversions
- fusions

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23
Q

Types of Mutations:
AT THE GENOME LEVEL

A
  • autopolyploidization
  • allopolyploidization
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24
Q

changes in the actual coding region of the gene

A

structural

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25
Q

structural

A
  1. primary
  2. secondary, tertiary, quaternary structure
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26
Q

primary structure

A

amino acid composition (amino acid substitutions)

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27
Q

changes in gene regulation

A

regulatory

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28
Q

regulatory

A

gene expression

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29
Q

gene expression

A
  • transcription
  • RNA processing
  • translation
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30
Q

single nucleotide change

A

point mutations

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31
Q

Causes of Point mutations

A
  1. DNA replication error during mitosis or meiosis
  2. Error in repair of sites damaged by mutagens
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32
Q

nucleotide composition

A
  1. phosphate group
  2. nitrogenous base
  3. 5’-carbon sugar
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33
Q

types of nitrogenous base

A
  1. purines
  2. pyrimidines
34
Q

purines mutate to purines
(ex. Adenine -> Guanine)

A

transitions

35
Q

link between sugar and phosphate

A

phosphodiester linkage

36
Q

purines mutate to pyrimidines, and vice versa
(ex. Adenine -> Cytosine)

A

transversions

37
Q

in the case of amino acids, what mutation position lead to amino acid change

A

position 1 and 2

38
Q

mutations that lead to amino acid changes (Position 1,2)

A

nonsynonymous substitutions (missense mutation)

39
Q

mutations that do not lead to amino acid change (often position 3)

A

synonymous substitutions (silent mutation)

40
Q
  • process by which a region of DNA coding for a gene is copied
  • can occur as the result of an error in recombination or through a retrotransposition event
  • genes are often immune to the selective pressure under which genes normally exist.
A

Gene duplication

41
Q

Gene duplications could happen due to..?

A
  1. “slippage” during DNA replication
  2. unequal crossing over during genetic recombination (meiosis)
42
Q
  • repeated segments are adjacent
  • often result from unequal crossing-over due to mispairing of homologous chromosomes during meiotic recombination
A

tandem duplications

43
Q

cause of mutation (gene duplication)

A

unequal crossing over

44
Q
  • segment of DNA that structurally resembles a gene but is not capable of coding for a protein
  • most often derived from genes that have lost their protein-coding ability due to accumulated mutations that have occurred over the course of evolution.
A

pseudogenes

45
Q

Fate of duplicated genes

A
  1. nonfunctionalization
  2. neofunctionalization
  3. subfunctionalization
46
Q

loss of function of extra gene copy

A

nonfunctionalization

47
Q

new function of extra gene copy

A

neofunctionalization

48
Q

partition of function between the gene copies

A

subfunctionalization

49
Q

different exons either within a gene or between two nonallelic genes are mixed (end up with new protein)

A

exon shuffling

50
Q

chromosomal alterations

A

chromosome
- duplications
- deletions
- inversions
- fusions

51
Q
  • DNA sequence that can change its relative position within the genome
  • “jumping genes”
A

transposable elements (transposons)

52
Q

discovered transposons or jumping genes

A

Barbara McClintock

53
Q

transposition “copy and paste”

A

retrotransposons

54
Q

transposition “cut and paste”

A

DNA transposons

55
Q

generation of more than two pairs of homologous chromosomes due to failure of reduction of chromosomes during cell division (mitosis or meiosis)

A

polyploidization

56
Q

vary among species and can vary among populations within a species

A

mutation rates

57
Q

rate of mutations in HIV

A

high

58
Q

in most species, mutations rate is relatively __

A

low

59
Q

when are elevated mutations rates advantageous

A

when faced with novel or stressful environments (especially in bactera)

60
Q

mutation rate is much higher in __ genomes relative to nuclear genomes

A

organelle

61
Q

why is mutation rate much higher in organelle genomes

A

due to lack of DNA repair enzymes

62
Q

mutation rate is elevated in some parts of the genome

A

mutational “hot spots”

63
Q

Evolutionary causes of mutation rate variation

A
  1. generation-time hypothesis
  2. metabolic-rate hypothesis
  3. DNA repair hypothesis
  4. genetic drift interfere with selection
64
Q
  • groups with shorter generations evolve faster because they experience more rounds of germ-cell divisions during an arbitrary unit of time
  • more rounds of germ-line divisions mean additional DNA synthesis and extra opportunities for mutations that are due to DNA replication errors
A

generation-time hypothesis

65
Q
  • mutation rate that is due to endogenous or exogenous mutagens, such as oxygen radicals
  • argues that groups with higher rates produce more free radicals, which leads to greater DNA damage and faster mutation and evolutionary rates
A

metabolic-rate hypothesis

66
Q
  • groups with better DNA repair systems
  • more mutations are corrected before transmission
  • reduces mutational output
A

DNA repair hypothesis

67
Q
  • in smaller populations, selection is less efficient, so fewer deleterious mutaitons are removed from the genome
  • increased presence of deleterious mutations in smaller populations
A

genetic drift interfere with selection

68
Q

most mutations in mutlicellular eukaryotes are __ with no effect on fitness, as most of the genome is nonfunctional

A

neutral

69
Q

most mutations that affect functional genes are __

A

harmful

70
Q

persist longer in population because it takes longer to select them out

A

mildly deleterious mutations

71
Q

selection for favorable mutations leads to __

A

adaptation

72
Q

mutations that matter, in evolutionary sense, are those that..?

A

passed on to next generation (occur in “germ line”)

73
Q

mutations that do not get passed on to the next generation

A

in somatic cells

74
Q

germ line that accumulates more mutations

A

male germ line

75
Q

discussed the exponential growth of mutations in the male germ line

A

James Crow

76
Q

mutation rate is constant with age

A

female germ line

77
Q

mutation rate increases exponentially with age

A

male germ line

78
Q

preferential or non-random use of synonymous codons

A

Codon usage bias

79
Q

what are the sources of genetic variation

A
  • mutation
  • genetic recombination
80
Q

Mutation that created a STOP codon

A

Nonsense mutation

BIO106 - Evolutionary Biology (20 decks)

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