Brainscape's Knowledge GenomeTM

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


See full index

Genomics > Molecular evolution > Flashcards

Molecular evolution Flashcards

1
Q

What are the concepts in Darwin’s “The Origin of Species” Theory?

A

Two concepts explain the current variety of life on Earth:

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

Explain natural selection.

A

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits

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

Define 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
4
Q

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

A

Genetic variation

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

What are genetic variant frequencies affected by?

A
  • selection
  • mutation
  • migration
  • genetic drift
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the relationship between selection and genetic variant frequencies?

A

genetic variants with a positive advantage will be selected for (and vice versa) because it will be more fit for its environment e.g.:

  • resistance to disease
  • ability to metabolise new food source
  • antibiotic resistance
  • change in appearance that enhances mate choice
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are conserved regions of the genome?

A

These regions are said to be resistant to change as they contain vital sequences

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

What are mutations in genetic variant frequencies?

A

the process by which variation in the genome arises

a rare variant may:

  • arisen recently
  • be deleterious
  • both (arisen recently and be deleterious)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is migration?

A

When there is physical movement of people from a different population resulting in new pools of variants being introduced to an existing population. This is known as admixture

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

What is genetic drift?

A

Genetic drift is how the frequency of a variant changes in a population due to chance
-all variants are subject to genetic drift

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

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

Which DNA sequences do not show much variation?

A

Any DNA sequence that is vital to the survival of an organism does not show much evidence of variation for obvious reasons.

Most variants in these regions 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
12
Q

What is sequence conservation (resistance to change)?

A

High Conservation Regions
-coding region (not exons as exons have non-coding regions)

Intermediate Conservation Regions
-promoter, 5’UTR, 3’UTR, terminator and splice site regions

Low Conservation Regions
-introns, 3rd base of codons and terminator regions

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

Why is there flexibility/low conservation in the third base of codons?

A

Because some amino acids are encoded by multiple codons

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

What can be used to see how a gene changes over time?

A

Cross-species comparison can be used to generate an evolutionary profile for .a gene or gene family to see how genes can changes over time

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

What is phylogenetics?

A

the study of evolutionary relationships and genetic connections among species

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

What is a phylogenetic tree?

A

A family tree that shows the evolutionary relationships thought to exist among groups of organisms

Distance between entities on a tree is usually related to how similar they are

17
Q

What is gene duplication?

A

duplication of DNA sequence containing a gene due to unequal crossing over during meiosis

18
Q

What is the Consequence of gene duplication?

A

one copy can continue being the original functioning gene and hence functioning protein

other copy diverges and can evolve new function(s) by changes in the coding sequence and/or control sequences (can also become pseudogene)

19
Q

What us unequal crossing over?

A

Misalignment of the two DNA molecules during crossing over, resulting in one DNA molecule with an insertion and the other with a deletion

These are typically low number repeat sequences

20
Q

What are globin gene clusters?

A

Two clusters:

  • Alpha-like are on chromosome 16, with 4 genes and 3 pseudogenes
  • Beta-like are on chromosome 11, with 5 genes and 1 pseudogene
21
Q

How are globin genes arranged?

A

in order of expression during development

22
Q

How have globin genes evolved?

A

through duplication and accumulation of mutations (divergence)

some are functioning genes and some are not (pseudogenes)

23
Q

How are globin genes expressed at different stages of development?

A

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

Embryo>Foetus>Postnatal

24
Q

What are the Predominant forms of haemoglobin?

A

HbF (foetal)- alpha and gamma

HbA (adult)- alpha and beta

25
Q

What are pseudogenes?

A

former genes that have accumulated mutations as a consequence of gene duplication over a long time and no longer produce functional proteins

-pseudogenes complicate PCR/sequencing/etc.

26
Q

What is sickle cell disease?

A

A human genetic disease caused by a recessive allele that results in the substitution of a single amino acid in the haemoglobin protein; characterised by deformed red blood cells that can lead to numerous symptoms.

“sickling” of red blood cells, which tends to block blood vessels

27
Q

When do symptoms of sickle cell disease arise? And why?

A

start at 5-6 months of age because there is a change in haemoglobin at this stage from HbF to HbA

28
Q

What are the Main symptoms of SCD?

A

Anaemia
-fatigue, restlessness, jaundice

Acute Pain Episode “Crisis”
-due to oxygen deprivation of tissues

Increased Frequency of Infections
-due to spleen damage

Stroke
Pulmonary Hypertension
Gallstones
Liver and Kidney Problems
Joint Problems
Delayed Puberty
29
Q

What is the cause of SCD?

A

Single base change in beta-globin gene of HbA

Codon changes from GAG (glutamic acid) to GTG (valine) at position 7 of the protein

30
Q

What is an Advantage of a sickle cell CARRIER?

A

one copy of the HbS variant confers resistance to severe malaria

this heterozygote advantage means that HbS variant is maintained in the population when otherwise it would have been selected against and lost

Genomics (19 decks)

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