Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

evolution > envs lecture 5 > Flashcards

envs lecture 5 Flashcards

1
Q

what provides material that selection acts on

A

mutation and variation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what would happen without variation in phenotype

A

nothing for natural selection to act on

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what provides new variation

A

mutation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

chromosome

A

strings of DNA bases bound together by proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is main structure in machinery of inheritance

A

chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are proteins in chromosomes

A

histones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

do all species have same number of chromosomes

A

no

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

locus

A

position on a chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

gene

A

physical unit of heredity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is gene composed of

A

DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is gene the code for

A

proteins and RNAs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is gene used interchangeably with

A

locus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

does a locus always code for protein

A

not always

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

is locus always part of a gene

A

not always

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

codons

A

sets of 3 DNA bases that are translated to AAs in protein-coding genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

synonymous codon/mutation

A

doesn’t change amino acid and thus protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

non-synonymous codon/mutation

A

changes amino acid, can cause sickle cell anemia etc.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

allele

A

alternative forms of a gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

homozygotes

A

carry exact same form on both chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

how many alleles for a given gene can an individual have

A

no more than two alleles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

how many alleles for a given gene can a population have

A

many different alleles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is genetic basis of variation in populations

A

population having many diff alleles for a given gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

central dogma

A

DNA –> RNA –> protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what does dNA code for

A

codons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what are codons transcribed to

A

RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what is RNA translated to

A

proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

SNP

A

single nucleotide polymorphism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what is SNP

A

single DNA base that defines alternative alleles at a locus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

example of SNP

A

likeee 2 alleles of gene XYZ differ at a SNP at position 242

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

homologous chromosomes

A

pair of chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

basically what is SNP

A

when a single base pair difference causes difference b/w two alleles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

exon

A

segments of a gene that code for amino acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

introns

A

noncoding DNA segments in between exons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

what is 1st step of protein synthesis

A

cell first transcribes DNA from genes into RNA (pre messenger RNA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

2nd step

A

pre mRNA is spliced, so parts of molecular are removed to form a mature mRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

3rd step

A

mRNA translated into a string of AAs that make up a protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

what happens in genomes where this process happens

A

segments of gene that are spliced out b/c they don’t encode AAs are introns

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

what are regions that do encode for AAs

A

exons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

purpose of introns?

A

variable, but we know they impact gene expression

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

how do introns impact gene expression

A

alternative splicing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

alternative splicing

A

allows a single gene to encode for more than one protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

summary of chromosomes & machinery of inheritance

A

organisms have chromosomes, within which are found protein coding genes, which are composed of codons, which can be changed to form diff versions of the same gene called alleles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

phneotype

A

observable characteristics of an organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

what does natural selection act on

A

phenotype

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

when does evolutionary change only occur

A

if phenotypes are heritable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

genotype

A

unique genetic makeup of an organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

are genotype and phenotype completely linked

A

not necessarily; b/c phenotype can be influenced by environment as well as genetics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

what happens if there’s no genetic variation and inheritance

A

no evolution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

segregation

A

separation of alleles during meiosis so that each gamete carries only one allele for each locus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

why is segregation important

A

all alleles have an equal change of being inherited in next gen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

hardy weinberg equilibrium

A

HWE characterizes distributions of genotype frequencies in populations that are NOT EVOLVING

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

what happens if genotypic frequencies in the population we’re studying are not at HWE

A

we need to explain this pattern via one of many processes causing evolutionary change in populations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

what does HWE provide

A

null model from which to understand process of genotypic & phenotypic evolution, based on what we expect due to chance alone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

when a population is in HWE, what is needed for equilibrium to be reached

A

when segregation is the only factor that influences genotype frequencies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

formula for genotype frequencies after one generation of random mating

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

what is p

A

frequency of homozygous genotypes (allele 1)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

what is 2pq

A

frequency of heterozygous genotypes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

what is q^2

A

frequency of homozygous genotypes (allele 2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

what is HWE

A

null model, reached under specific set of conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

first HWE condition

A

mating is random

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

second HWE condition

A

population size is very large (inifinte)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

3rd HWE condition

A

gene flow does not occur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

4th HWE condition

A

mutation doesn’t occur [negligible anyway]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

5th HWE condition

A

locus concerned is not under selection (no fitness difference b/w alleles)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

why is this null model even useful

A

observed in natural populations; find it in nature when mating is random w/r to genotype at most loci in genome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

so basically why is HWE interesting

A

deviations from HWE tell us that a locus is involved in an interesting evolutionary process

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

how to find frequency of A allele

A

add freq of homozygotes and half freq of heterozygote

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

a mechanism by which genetic variation is produced & inherited (i.e. evolution is allowed to occur)

A

recombination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

recombination

A

occurs in meiosis & gamete production –> produces new genetic combos within a gamete

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

how does recombination occur

A

by independent assortment or crossing over

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

law of independent assortment / crossing over

A

the allele a gamete receives for one gene doesn’t influence the allele it gets for a different gene

72
Q

what does law of independent assortment produce

A

novel combos of alleles in gametes

73
Q

what two mechanisms can recombination occur through

A

independent assortment or crossing over

74
Q

what is crossing over

A

when homologous chromosomes swap segments of DNA

75
Q

what happens to loci in crossing over

A

loci on same chromosome can recombine by crossing over

76
Q

basically what is crossing over

A

process that involves genes linked on the same chromosome undergoing recombination

77
Q

what happens to chromosomes in meiosis

A

homologous chromosomes are aligned, crossing over occurs, exchanging pieces of the homologous chromosomes (which might be carrying different alleles)

78
Q

what does crossing over prodouce

A

both recombinant and non-recombinant chromatids

79
Q

what happens to recombinant ones

A

the ones resulted from exchanging pieces of chromosomes during crossing over

80
Q

what does process of crossing over do

A

produces new associations and combos of alleles in multiple genes on a given chromosome, thus increases genetic variation

81
Q

recombination & segregation

A

powerful tools that promote novel genetic combinations that can be inherited in future generations

82
Q

what do both recombination and segregation do

A

produce and promote novel genetic combos that are inherited by future generations

83
Q

recombination rate (r)

A

probability that recombination occurs between a given pair of loci

84
Q

what happens of two loci are on different chromosomes

A

r = 1/2

85
Q

if two loci are on the same chromosome

A

r < 1/2

86
Q

what happens of loci are on different chromosomes

A

50% chance that when an individual makes a gamete one of the chromosomes it carries will be from the mother and other from the father

87
Q

what happens of the loci are on the same chromosome

A

closer the loci are, smaller r

88
Q

what happens to loci right next to each other

A

r = 0

89
Q

linkage disequilibrium

A

alleles of multiple loci are found together more often than you would expect based on independent assortment

90
Q

another way to think about LD

A

allelic association

91
Q

what does LD suggest

A

different loci are physically linked on the same chromosome

92
Q

is LD actually the case

A

not necessarily (often isn’t)

93
Q

when does linkage disequilibrium occur

A

when recombination rate is low

94
Q

why does LD occur when recombination rate is low

A

b/c it acts to mix the association of alleles at different loci

95
Q

what happens to loci close together in linkage disequilibrium

A

loci closer together experience less recombination (lower r) and higher linkage

96
Q

what causes linkage disequilibrium

A

linkage disequilibrium can result from other processes besides physical proximity on a chromosome

97
Q

what else can cause LD

A

natural selection, genetic drift

98
Q

example of nat selection causing LD

A

epistasis

99
Q

epistasis

A

when the effect of an allele at one locus depends on the allele at a second locus

100
Q

when does selection promote linkage

A

when combos of alleles have high fitness

101
Q

example of LD in primrose

A

plants either have low anthers/high stigma or high anthers/low stigma; two traits are at linkage disequilibrium b/c specific combos have higher fitness

102
Q

gene mixing without inheritance

A

horizontal gene transfer (HGT)

103
Q

HGT

A

movement of DNA between individuals without sexual reproduction

104
Q

what is HGT common in

A

prokaryotes

105
Q

vertical gene transfer

A

how genetic variation is produced in sexually reproducing organisms

106
Q

why is HGT iimportatn

A

how antibiotic resistance is spread and transferred across bacteria

107
Q

bacterial transformation

A

spread of antibiotic resistance; donor cell releases DNA that is taken up by a recipient cell

108
Q

how is that variation ultimately produced

A

mutations

109
Q

mutation

A

ultimate source of genetic variation in all organisms

110
Q

what would happen w/o mutations

A

no variation, no evolution

111
Q

types of mutations

A

point mutation, structural mutation

112
Q

point mutation

A

single base pair mutation

113
Q

structural mutation

A

insertions/deletions (single to multiple bases), inversion (DNA segment), fusion/fission (chromosomes), whole genome amplification (all DNA in genome)

114
Q

what are point mutation

A

single nucleotide changes

115
Q

what can point mutations be

A

synonymous, nonsynonymous, can cause stop codon

116
Q

what do stop codons produce

A

pseudogenes (nonfunctional)

117
Q

ice fish

A

colorless blood b/c it lacks hemoglobin; either genes are deleted or rendered nonfunctional (point mutation) (pseudogenes)

118
Q

what are most mutations at 3rd codon position

A

synonymous

119
Q

what are all mutations at 2nd position

A

non-synonymous

120
Q

what is synonymous

A

don’t change AAs

121
Q

what are nonsynonymous

A

change AAs

122
Q

types of chromosomal mutation

A

deletion, duplication, inversion, fission, fusion,

123
Q

deletion

A

DNA segment is removed

124
Q

duplication

A

DNA segment is copied and inserted in the genome/chromosome

125
Q

inversion

A

chromosome segment is reversed

126
Q

fission

A

one chromosome breaks into two

127
Q

fusion

A

two chromosomes become 1

128
Q

what do fission/fusion do

A

alter number of chromosomes in the genome

129
Q

what is whole genome duplication

A

occurs when meiosis produces gametes that carry a diploid genome which then undergo fertilization

130
Q

which organisms have whole genome duplications?

A

common in plants; occurred deep in evolutionary history of many plant lineages

131
Q

whole genome duplication is important source of what

A

evolutionary novelty

132
Q

what does double the genes mean (WGD)

A

opportunity for new functions to evolve

133
Q

why is WGD important source of evolutionary novelty

A

b/c having double the number of genes provides opportunity for new functions to evolve

134
Q

is DNA replication accurate

A

extremely

135
Q

what do mistakes in DNA replication lead to

A

mutations

136
Q

how much of DNA bases are a mutant in humans

A

1 out of every 10^8 (100 million) bases

137
Q

given 3 billion base pairs, each gamete has how many mutations

A

approximately 30 mutations

138
Q

is mutation rate variable among tree of life

A

yeah

139
Q

who has more mutation rates

A

parasites and viruses have higher mutation rates than hosts

140
Q

why might it be advantageous to have high mutation rates

A

produces novel variation, allows them to evolve and keep evading hosts

141
Q

fitness

A

number of offspring an organism produces

142
Q

beneficial mutations

A

increase fitness

143
Q

are beneficial mutations rare or common

A

rare

144
Q

what are beneficial mutations acted on

A

acted on by natural selection

145
Q

what are deleterious mutations

A

decrease fitness

146
Q

are deleterious mutations rare or common

A

more common

147
Q

are deleterious mutations acted on or selected against

A

selected against

148
Q

pleiotropy

A

occurs when single mutation affects multiple traits

149
Q

what is currency of natural selection

A

fitness

150
Q

what do most genetic changes likely have

A

pleiotropic effects (side effects)

151
Q

do synonymous mutations have an effect on fitness

A

not really; almost no effect

152
Q

what do majority of mutations have

A

negative effects; deleterious

153
Q

are beneficial mutations common or rare

A

rare; very few mutations are beneficial

154
Q

germ line mutations

A

mutation in gamete (germ cell –> egg or sperm)

155
Q

are germ line mutations inherited

A

yes

156
Q

what are germ cells

A

egg or sperm

157
Q

what is gamete

A

germ cell; egg or sperm

158
Q

are somatic mutations inherited

A

no

159
Q

who does somatic mutations effect

A

the bearer

160
Q

somatic cell

A

body cell

161
Q

is mutation random

A

yes and no

162
Q

how is mutation not random

A

not random because certain types of mutations are favored

163
Q

what types of mutations are favored

A

transitions are more common than transversions, even though there are twice as many transversion mutations

164
Q

transitions

A

mutations between A and G or C and T (purine to purine, pyrimidine to pyrimidine)

165
Q

transversions

A

all other mutations

166
Q

how is mutation random

A

fitness effects of mutations are truly random

167
Q

how is fitness effects of mutations truly random

A

organism isn’t more likely to evolve beneficial mutations b/c of a strong selective pressure (but selection will act if a mutation is beneficial)

168
Q

when will selection act

A

if mutation is beneficial

169
Q

HOWEVER; what’s up w/ mutational hotspots

A

mutational hotspots may make adaptation more likely if a mutational hotspot lies within a locus w/ important function

170
Q

non genetic inheritence

A

epigenetics

171
Q

epigenetics

A

study of changes in expression of genes

172
Q

what is non genetic inheritance

A

form of inheritance that does not require changes to DNA

173
Q

what is expression

A

transcription of DNA into RNA; first step of formation of protein

174
Q

what can prevent genes from being expresed

A

methylation and histone modification of DNA

175
Q

can these methylation and histone modifications be inherited

A

yeah

176
Q

are these non genetic inheritance long term??

A

not rlly for long term evolutionary chage

evolution (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions