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CELS191 > Molecular Biology & Genetics 6 - Population Genetics & Natural Selection+ Sequencing the Human Genome > Flashcards

Molecular Biology & Genetics 6 - Population Genetics & Natural Selection+ Sequencing the Human Genome Flashcards

1
Q

What is a population?

A

Localised group of individuals of the same species

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2
Q

What is the gene pool?

A

Total aggregate of genes (and their alleles) in the population at one time

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3
Q

Why do we need to estimate genotype frequencies?

A

To predict how many individuals will inherit a genetic disease and to estimate the proportion of individuals. who are carriers of a genetic disease as this can’t be observed

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4
Q

How do we estimate the genotype frequencies?

A

Using the hardy-weinberg equation

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5
Q

What is the hardy Weinberg equation?

A

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

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6
Q

What is p^2?

A

The proportion of homozygous dominant

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7
Q

What is 2pq?

A

The proportion of heterozygous

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8
Q

What is q^2?

A

The proportion of homozygous recessive

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9
Q

What is the allele frequency equation?

A

p+q=1

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10
Q

What is p?

A

The frequency of the dominant allele

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11
Q

What is q?

A

The frequency of the recessive allele

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12
Q

How can allele frequencies change?

A

By non random mating, random genetic drift, the bottleneck effect, the founder effect, natural selection, mutations and migration

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13
Q

What are types of non-random mating?

A

Assortative mating and inbreeding

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14
Q

What is assortative mating?

A

When a particular genotype is more likely to mate with the genotype the same as themselves

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15
Q

What is inbreeding?

A

Breeding with a related individual which isn’t always avoidable in smaller populations

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16
Q

What is random genetic drift?

A

A random change in the allele frequencies due to sampling error over generations

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17
Q

What does random genetic drift depend on?

A

The mating combinations and how many individuals mate

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18
Q

What is random genetic drift noticeable in?

A

Particularly in small populations

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19
Q

What is the result of a population bottleneck/reduction event?

A

Loss or decrease in frequency of some alleles and decreased genetic diversity

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20
Q

What is the founder effect?

A

A population bottleneck as a result of a new population being established

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21
Q

What is genetic diversity of new populations dependent on?

A

The founders and is often less diverse than the original population

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22
Q

What are the types of natural selection?

A

Stabilising selection, directional selection, disruptive selection and sexual selection and frequency dependent selection

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23
Q

What happens in stabilising selection?

A

The medium individual phenotype is favoured by natural selection. The peak gets higher and narrower

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24
Q

What is the result of stabilising selection?

A

Reduces variation but doesn’t change the mean

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25
Q

What happens in directional selection?

A

Larger or smaller individual phenotype is favoured by natural selection. The peak shifts in one direction.

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26
Q

What is the result of directional selection?

A

Changes the mean value towards one extreme

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27
Q

What happens in disruptive selection?

A

Large and small phenotypes are favoured by natural selection forming two peaks

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28
Q

What is the result of disruptive selection?

A

Favours two extremes producing two peaks

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29
Q

What is sexual selection?

A

When males have features (e.g. long tails/feathers) which attract females and the “better” this is the more likely they are to attract a female

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30
Q

What is frequency dependent selection?

A

The rare (low frequency) individual obtains more food and becomes more common but then the other individual does better and balances this effect out

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31
Q

What is a mutation?

A

Very slow to act and usually disadvantageous, its role is usually of macroevolutionary proportions

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32
Q

What is migration ?

A

When an individual from another population successfully mates and contributes gametes to the gene pool

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33
Q

What are the results of migration?

A

Bringing new alleles, changing proportions of existing alleles, changing population size, making two populations more similar

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34
Q

What is cline?

A

The gradual geographic change in genetic/phenotypic composition

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35
Q

When did the human genome project begin?

A

1990

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36
Q

What did the human genome project aim to identify?

A

All human genes and their roles

37
Q

What did the human genome project aim to analyse?

A

Genetic variation between humans

38
Q

What did the human genome project aim to sequence?

A

The genomes of several model organisms used in genetics

39
Q

What did the human genome project aim to develop?

A

New sequences and computational analyses

40
Q

What did the human genome project aim to share?

A

Genome information with scientists and the general public as fast as possible

41
Q

What is a genome?

A

A complete set of DNA of an organism, including all its genes

42
Q

What is genomics?

A

The study of genomes

43
Q

What does nuclear DNA consist of?

A

22 autosomes, X and Y

44
Q

What does mitochondrial DNA consist of?

A

Single, circular DNA

45
Q

How many base pairs in nuclear DNA?

A

6 billion

46
Q

How many base pairs in mitochondrial DNA?

A

16,569

47
Q

Where does nuclear DNA come from?

A

Half from each parent

48
Q

Where does mitochondrial DNA come from?

A

All from the mother

49
Q

How many genes in nuclear DNA?

A

<21,000

50
Q

How many genes in mitochondrial DNA?

A

37 genes

51
Q

What is the human reference genome made up of?

A

Lots of different people

52
Q

What were some of the key findings of the human genome?

A

There are fewer genes than expected, the genome is dynamic, most human genes are related to those of other animals

53
Q

What do we still not know about the human genome?

A

What many of our protein coding genes do

54
Q

How similar are humans?

A

All humans are 99.9% similar at sequence level

55
Q

How much of the genome codes for proteins?

A

Less than 2%

56
Q

How much of the genome codes for introns?

A

20%

57
Q

How many genes have unknown function still?

A

About 25%

58
Q

While any two human genomes are 99.9% similar…

A

across the population, there is a lot of variation and it is important (for natural selection)

59
Q

What are single nucleotide polymorphisms (SNP’s)?

A

Sites in the DNA that commonly vary within populations- common single base pair changes or variants

60
Q

How many SNP’s are there?

A

1.9 million

61
Q

How common are SNP’s?

A

common- around 1 in every 300 nucleotides

62
Q

Where do SNP’s come from?

A

Mostly from parents (half from mother and half from father)

63
Q

What does each genome sequenced do?

A

Adds to the variation on record

64
Q

What does diversity in genome sequencing do?

A

Adds to the knowledge of variation

65
Q

What do many SNP’s do?

A

The don’t do anything, they are just inherited variations but that doesn’t mean they’re not useful

66
Q

What can genotyping tell you?

A

Who you are related to, where (some of) your ancestors are from, disease risk/association, if you will lose your hair, your muscle type, how you might respond to drugs

67
Q

What can genotyping also be used for?

A

In crime solving

68
Q

What do some of our SNP’s reveal?

A

Our species ancestral interbreeding with other hominins

69
Q

Where are linked SNP’s found and what do they do?

A

Found outside of a gene and have no effect on protein production or function

70
Q

Where are causative SNP’s found?

A

In the gene

71
Q

What are the two types of causative SNP’s?

A

Coding SNP’s and non-coding SNP’s

72
Q

What do coding SNP’s do?

A

change the amino acid sequence and therefore the protein produced

73
Q

What do non-coding SNP’s do?

A

change the amount of a protein produced

74
Q

What happens if the second or third base is the SNP?

A

they are less likely to affect the amino acid, protein and therefore phenotype

75
Q

What are short tandem repeats (STR’s)?

A

Repeats of 2-5 nucleotides found in specific regions of the genome

76
Q

What does each person inherit with respect to STR’s?

A

2 alleles, one from each biological parent, which can be different lengths

77
Q

What can STR’s be used for?

A

To create genetic profiles or “DNA fingerprints”

78
Q

What are indels?

A

small insertions or deletions

79
Q

Are insertions or deletions more common?

A

Deletions

80
Q

What is the second most common variant type in the human genome?

A

Indels

81
Q

How many indels are there?

A

0.2 million

82
Q

What can indels cause?

A

A frameshift which is a change in the way DNA is read if in protein coding regions

83
Q

What are copy number variations?

A

Chunks of DNA >500 base pairs that are present at different amounts or “copy numbers” relative to a reference genome

84
Q

What can copy number variants be?

A

deleted or duplicated

85
Q

What can copy number variations do?

A

Span multiple genes

86
Q

How many CNV’s do humans have?

A

10,000 found within and between genes

87
Q

What are many genes in CNV’s associated with?

A

Sensory perception and immunity

88
Q

How many large CNV’s are there and how many genes do they affect?

A

23 and they effect 34 genes

CELS191 (23 decks)

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