Lesson 6: Mutation Flashcards
1
Q
- genetic substrate for natural selection
- raw material for evolution
A
mutation
2
Q
What reduces variation?
A
- genetic drift in finite populations
- reduction in allelic diversity
- reduction in heterozygosity (inbreeding)
3
Q
Sources of allelic variation
A
mutation
4
Q
Sources of Genotypic Variation
A
Sex (meiosis)
5
Q
heritable variation changes in gene expression without changes in genetic code
A
epigenetic inheritance
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
7
Q
requires genetic variation upon which it could act
A
natural selection
8
Q
- change in genetic code
- new alleles and/or new genes
A
mutations
9
Q
Mutations: new alleles
A
nucleotide substitutions, insertions, deletions
10
Q
Mutations: new genes
A
- gene duplication or deletions
- exon shuffling
- horizontal gene transfer (not always considered mutation)
11
Q
Types of Mutations
A
- chromosomal duplications or deletions
- deletions of large chromosomal regions
- chromosomal inversions
- whole genome duplication
12
Q
- no novel alleles
- only novel genotypes
A
sex
13
Q
Sex
A
- genetic recombination
- random mating
14
Q
shuffling of combinations of alleles along a chromosome
A
genetic recombination
15
Q
shuffling of combinations of haploid chromosomes into new genotypes
A
random mating
16
Q
Types of Mutations:
AT THE NUCLEOTIDE LEVEL
A
- single nucleotide substitutions
- insertions
- deletion
17
Q
mutation at the nucleotide level is also called…?
A
point mutations
18
Q
types of single nucleotide substitutions
A
- transitions
- transversions
19
Q
Types of Mutations:
AT THE “GENE” LEVEL
A
- gene insertions
- gene deletions
- exon shuffling
20
Q
Types of gene insertions
A
- gene duplication
- transposons
- horizontal gene transfer
21
Q
Types of gene deletions
A
- pseudogenization
- transposons
22
Q
Types of Mutations:
AT THE CHROMOSOME LEVEL
A
chromosome
- duplications
- deletions
- inversions
- fusions
23
Q
Types of Mutations:
AT THE GENOME LEVEL
A
- autopolyploidization
- allopolyploidization
24
Q
changes in the actual coding region of the gene
A
structural
25
structural
1. primary
2. secondary, tertiary, quaternary structure
26
primary structure
amino acid composition (amino acid substitutions)
27
changes in gene regulation
regulatory
28
regulatory
gene expression
29
gene expression
- transcription
- RNA processing
- translation
30
single nucleotide change
point mutations
31
Causes of Point mutations
1. DNA replication error during mitosis or meiosis
2. Error in repair of sites damaged by mutagens
32
nucleotide composition
1. phosphate group
2. nitrogenous base
3. 5'-carbon sugar
33
types of nitrogenous base
1. purines
2. pyrimidines
34
purines mutate to purines
(ex. Adenine -> Guanine)
transitions
35
link between sugar and phosphate
phosphodiester linkage
36
purines mutate to pyrimidines, and vice versa
(ex. Adenine -> Cytosine)
transversions
37
in the case of amino acids, what mutation position lead to amino acid change
position 1 and 2
38
mutations that lead to amino acid changes (Position 1,2)
nonsynonymous substitutions (missense mutation)
39
mutations that do not lead to amino acid change (often position 3)
synonymous substitutions (silent mutation)
40
- 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.
Gene duplication
41
Gene duplications could happen due to..?
1. "slippage" during DNA replication
2. unequal crossing over during genetic recombination (meiosis)
42
- repeated segments are adjacent
- often result from unequal crossing-over due to mispairing of homologous chromosomes during meiotic recombination
tandem duplications
43
cause of mutation (gene duplication)
unequal crossing over
44
- 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.
pseudogenes
45
Fate of duplicated genes
1. nonfunctionalization
2. neofunctionalization
3. subfunctionalization
46
loss of function of extra gene copy
nonfunctionalization
47
new function of extra gene copy
neofunctionalization
48
partition of function between the gene copies
subfunctionalization
49
different exons either within a gene or between two nonallelic genes are mixed (end up with new protein)
exon shuffling
50
chromosomal alterations
chromosome
- duplications
- deletions
- inversions
- fusions
51
- DNA sequence that can change its relative position within the genome
- "jumping genes"
transposable elements (transposons)
52
discovered transposons or jumping genes
Barbara McClintock
53
transposition "copy and paste"
retrotransposons
54
transposition "cut and paste"
DNA transposons
55
generation of more than two pairs of homologous chromosomes due to failure of reduction of chromosomes during cell division (mitosis or meiosis)
polyploidization
56
vary among species and can vary among populations within a species
mutation rates
57
rate of mutations in HIV
high
58
in most species, mutations rate is relatively __
low
59
when are elevated mutations rates advantageous
when faced with novel or stressful environments (especially in bactera)
60
mutation rate is much higher in __ genomes relative to nuclear genomes
organelle
61
why is mutation rate much higher in organelle genomes
due to lack of DNA repair enzymes
62
mutation rate is elevated in some parts of the genome
mutational "hot spots"
63
Evolutionary causes of mutation rate variation
1. generation-time hypothesis
2. metabolic-rate hypothesis
3. DNA repair hypothesis
4. genetic drift interfere with selection
64
- 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
generation-time hypothesis
65
- 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
metabolic-rate hypothesis
66
- groups with better DNA repair systems
- more mutations are corrected before transmission
- reduces mutational output
DNA repair hypothesis
67
- in smaller populations, selection is less efficient, so fewer deleterious mutaitons are removed from the genome
- increased presence of deleterious mutations in smaller populations
genetic drift interfere with selection
68
most mutations in mutlicellular eukaryotes are __ with no effect on fitness, as most of the genome is nonfunctional
neutral
69
most mutations that affect functional genes are __
harmful
70
persist longer in population because it takes longer to select them out
mildly deleterious mutations
71
selection for favorable mutations leads to __
adaptation
72
mutations that matter, in evolutionary sense, are those that..?
passed on to next generation (occur in "germ line")
73
mutations that do not get passed on to the next generation
in somatic cells
74
germ line that accumulates more mutations
male germ line
75
discussed the exponential growth of mutations in the male germ line
James Crow
76
mutation rate is constant with age
female germ line
77
mutation rate increases exponentially with age
male germ line
78
preferential or non-random use of synonymous codons
Codon usage bias
79
what are the sources of genetic variation
- mutation
- genetic recombination
80
Mutation that created a STOP codon
Nonsense mutation
