Brainscape's Knowledge GenomeTM

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


See full index

Genomics SGUL Sem 3 > Molecular evolution > Flashcards

Molecular evolution Flashcards

1
Q

What is ‘on the origin of species’ about?

A

Theory to explain the current variety of life on earth

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

What are the two main concepts in ‘the origin of species’?

A

Natural selection and fitness

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

What is the definition of natural selection?

A

The effects of a wide range of factors on the frequency of heritable changes in a species

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

What is the definition of fitness?

A

How well a species is able to reproduce in its environment

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

What is the relationship between fitness ad selection?

A

→ Anything that increases fitness is selected for
→ anything that decreases fitness is selected against

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

What happens to neutral changes?

A

They vary randomly

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

What is modern synthesis?

A

Unifying evolution with genetics to explain the molecular processes underlying evolution

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

What is the main source of heritable variation in a species?

A

Genetic variation

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

What 4 things are the frequency of genetic variants affected by?

A

→ Selection
→ Mutation
→ Migration
→ Genetic drift

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

What types of genetic variants are selected for?

A

Variants that confer a positive advantage

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

What is an example of a positive advantage?

A

→ resistance to disease
→ an ability to metabolise a new food source
→ change in appearance to enhance mate choice

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

What parts of the genomes are resistant to change and why?

A

→ They are conserved
→ because they contain vital sequences

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

What is mutation?

A

Process by which variation arises

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

What does genomic variant frequency depend on?

A

→ Selection
→ When the variants first occurred

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

What are the three possibilities of low frequency in a rare variant?

A

→ May have arisen recently
→ be deleterious and being selected against

→ both

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

What is migration and what does this result in genetically and what is this called?

A

→ Physical movement from a different population
→ Result in new pools of variants being introduced to an existing population

→ Admixture

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

Why does admixture need to be taken into account when studying populations?

A

Population frequencies of specific variants can change purely due to admixture and not be disease related

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

What is genetic drift?

A

How the frequency of a variant changes in a population due to chance

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

What are 2 reasons that variation is not passed on?

A

→ Not all organisms will pass on their genetic variants
→ mechanisms such as recombination will also result in not all variants being passed on

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

What are all variants subject to?

A

Genetic drift

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

What types of sequences don’t show variation?

A

DNA sequences that is vital to the survival of an organism

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

What happens if variants occur in conserved regions?

A

They will be selected against as they are likely to have a strong deleterious effect

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

Why is there some flexibility in variation in conserved regions?

A

there is flexibility in the third base of codons as some amino acids are encoded by multiple codons

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

Where is high conservation seen and what is the exception?

A

→ Coding regions
→ but not in exons as they have non coding regions
→The further you move on the tree from us, the less introns we have in common with them

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

Where is intermediate conservation seen?

A

→ promoter
→ 5’ UTR

→ Splicing sites
→ 3’ UTR
→ Terminator

26
Q

Where is low conservation seen?

A

→ Introns
→ 3rd base of codons

→ Terminator (vague signals such as GC rich regions)

27
Q

What can be used to generate an evolutionary profile and why?

A

→ Cross species comparison
→ To see how genes change over time

28
Q

What is phylogenetics?

A

Working out the history of the genome

29
Q

What is needed for phylogenetic sequencing?

A

→ Observe sequences
→ See how are they related

30
Q

What does a phylogenetic tree show?

A

Illustrate relatedness of different species

31
Q

What does distance show on a phylogenetic tree?

A

→ The more distance the less related they are
→ distance is related to both evolutionary pressures and time

32
Q

How is time estimated on phylogenetic trees?

A

Measuring mutation rates

33
Q

What is the theory behind the introduction of HIV to the human population?

A

→ a contaminated polio vaccine
→ some polio vaccines were produced with cultured chimpanzee cells which could have been infected with SIV

34
Q

What is gene duplication?

A

Duplication of a DNA sequence containing a gene, can be multiple genes

35
Q

What is the typical mechanism of gene duplication?

A

Unequal crossing over

36
Q

What are the two options after duplication?

A

→ One copy can continue the original function
→ the other copy can evolve new functions by changes in the coding or control sequences
→Means possibilities of related genes arising that allows better adaptation.

37
Q

What is unequal crossing over?

A

→ Recombination between sequences that are not the correct sequence but are very similar
→ often low copy number repeat sequences

38
Q

When does unequal crossing over usually happen?

A

Often low copy number repeat sequences

39
Q

How many clusters of the globin gene are there?

A

2

40
Q

Where are the alpha like globin genes?

A

→ chromosome 16
→ 3 genes

→ 3 pseudogenes

41
Q

Where are the beta like globin genes?

A

→ chromosomes 11
→ 5 genes and one pseudo gene

42
Q

How are the globin genes arranged?

A

In order of expression during development

43
Q

What are the 3 types of Hb?

A

→ Embryonic
→ Fetal

→ Postnatal

44
Q

What is the control region of the beta globin cluster?

A

Beta LCR (locus control region)

45
Q

How have globin genes evolved?

A

Divergence

46
Q

What are pseudogenes?

A

Non functioning genes

47
Q

What allows the expression of globin genes at different stages?

A

Divergence of promoters has occurred so they bind different transcription factors and allow expression of genes at different stages of development

48
Q

What is fetal Hb made from?

A

Alpha and gamma subunits

49
Q

What is adult Hb made from?

A

Alpha and beta subunits

50
Q

How are pseudogenes formed?

A

After gene duplication one gene maintains original function and the other diverges

51
Q

What do pseudogenes contain?

A

Many mutations and are non functional

52
Q

When do sickle cell symptoms start and why?

A

→ 5- 6 months
→ change between HbF and HbA

53
Q

What are the symptoms of sickle cell?

A

→ Anaemia
→ Acute pain episodes - crises - due to oxygen deprivation

→ Increased infection
→ stroke, hypertension

54
Q

What are the symptoms due to?

A

Sickling of red blood cells

55
Q

How does sickle cell occur?

A

A single base change in the beta globin gene of HbA

56
Q

What is the codon change in sickle cell?

A

→ GAG to GTG
→ Glutamine to valine at position 6

57
Q

What kind of a disease is sickle cell?

A

Autosomal recessive

58
Q

What is the chance of a child getting SCD if the parents have 1 copy each?

A

1 in 4

59
Q

What is the distribution of HbS?

A

→ Africa
→ Middle east
→ India

60
Q

Why has sickle cell not been selected against?

A

→ with one copy of HbS it improves reproductive fitness
→ because it confers resistance to severe malaria

61
Q

What does heterozygote advantage mean for HbS?

A

The variant is maintained because of the huge selection pressure

Genomics SGUL Sem 3 (21 decks)

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