Genes and Populations Flashcards

1
Q

the Hardy-Weinberg assumptions?

A

1 – individuals in the population mate at random – there is no assortative mating

2 – no migration from other populations changes the allele frequency

3 – no new mutation in any genes arises

4 – population size is infinite and therefore there are no chance effects on allele frequency

5 – natural selection is not acting on any of the alleles

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

the Hardy-Weinberg equations describe an …

A

…ideal scenario

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

How do individuals choose who to mate with?

A
  • At random
  • Assortative mating
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

A possible driver of speciation via natural selection is…

A

…assortative mating

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

Why are some populations get driven apart from mating?

A

when they are no longer physically together when mate choice is decided

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

Entire populations can be subdivided by…

A

…geographical barriers

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

There is..

A

…gene flow between populations

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

What is gene flow sometimes also known as?

A

rate of migration

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

if migration is large enough it will …

A

…act to counterbalance differences in allele frequencies of different populations

  • in effect they become one population
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

the persistence of a mutation and the spread of an allele through a population depends on …

A

…whether the mutation has a deleterious or advantageous effect and whether it is dominant or recessive

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

most mutations will be…

A

most mutations will be deleterious

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

What are recessive lethals?

A

Chance effects

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

why is the population being of infinite size an important assumption of the HW equations?

A

This is known as genetic drift – the effect of chance. Random chance.

the larger the population the less chance has an effect

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

A severe drop in population size can cause…

A

…the bottleneck effect

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

WHen a population passes through a bottle neck…

A

…its size is reduced.

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

define monoallelic

A

one allele

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

Natural selection disrupts…

A

…HW equilibrium

18
Q

natural selection affects…

A

allele frequencies

19
Q

What affects allele frequencies?

A
  • Bottleneck effects
  • Founder effects
  • Natural selection
  • Mutation
  • Population size
  • Migration
  • Assortative mating
20
Q

what kind of mutation might be behind lactose tolerance? is this likely to be dominant or recessive?

A

Promoter mutated. Promoter changes shape so that transcription factor cannot bind. Lactase cannot turn on, hence lactose intolerance. A dominant mutation.

21
Q

What mutation in which gene is responsible for the presence of dry earwax?

A
  • a mutation in the ABCC11 gene
22
Q

What does mutated gene ABCC11 encode?

A

it encodes a transporter protein sitting in the plasma membrane – involved in secretion

23
Q

What does mutated gene ABCC11 effect?

A

effects the production of cerumen but.. also the mutation reduces axillary sweating – hence is advantageous in northern latitudes

24
Q

sometimes it is not allele frequency that can be manipulated by natural selection but …

A

…genotype frequency

  • the classic example is sickle cell anaemia
25
What causes sickle cell anaemia?
caused by a point mutation in the gene that encodes the β-globin chain of haemoglobin (Hbβ)
26
What type of disorder is sickle cell anaemia?
an inherited disorder.
27
What does mutation of Hbβ result in?
- mutation results in the replacement of negatively charged glutamate by a neutral, hydrophobic valine - this change produces sticky patches on the protein surface
28
what is mutant haemoglobin gene?
HbS
29
mutant haemoglobin (HbS) polymerizes into ...
...fibres, which distort red blood cells
30
Why does sickle cell anaemia cause pain?
blockage of the circulation, resulting in acute, severe pain
31
in some regions the sickle-cell allele can reach frequencies as high as ...
...15-20%
32
Advantage of sickle cell anaemia?
- heterozygote advantage – protection against malaria
33
WHats the most common adult form of haemoglobin ?
haemoglobin A
34
Sickle cell anaemia is the result of...
...mutation in the beta subunits (green)
35
haemoglobin will polymerise in ...
...low oxygen conditions – rbc shape - long rigid
36
the examples we see in Mendel are chosen by ...
...artificial selection
37
What causes sickle cell anaemia?
alteration of the haemoglobin A gene by one amino acid causes change in the function of the protein – valine at position 6 causes hydrophobic collapse and the molecules can form polymers resulting in sickle-shaped red blood cells.
38
Why does sickle cell anaemia persist?
Glutamate binds to valine causing a change in shape/structure. Changes the way the surface of the cell reacts.
39
We can use data from Hardy Weinberg equation to...
...quantify relative fitness (w) of genotypes in this case
40
What value do we use as the fittest value?
we use the top value as the fittest value