Molecular Evolution

Question 1

What is natural selection?

Answer 1

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

Question 2

What is fitness?

Answer 2

How well a species can reproduce in its environment

Question 3

What is the modern synthesis?

Answer 3

Evolution can be unified with genetics to explain molecular processes underlying evolution

Question 4

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

Answer 4

Genetic variation

Question 5

What are the four things that affect frequency of genetic variants?

Answer 5

Selection, mutation, migration and genetic drift

Question 6

How does selection affect the frequency of genetic variants?

Answer 6

Variants that give a positive advantage will be selected for, however some vital genome sequences are conserved

Question 7

How does mutation affect the frequency of genetic variants?

Answer 7

The process by which variation in the genome arises

Question 8

What do mutation frequencies depend on?

Answer 8

Selection and when they first arose

Question 9

What is it called when migration affects the frequency of genetic variants?

Answer 9

Admixture

Question 10

What does admixture mean?

Answer 10

The movement of people from a different population results in new pools of variants being introduced into an existing population

Question 11

How does genetic drift affect the frequency of genetic variants?

Answer 11

The frequency of variants changing due to chance - not all variations will be passed on

Question 12

Why does sequence conservation happen?

Answer 12

To stop vital proteins being lost

Question 13

Where is there high conservation?

Answer 13

Coding regions

Question 14

Where is there intermediate conservation?

Answer 14

Promoter, 5’UTR, 3’UTR and terminator regions

Question 15

Where is there low conservation?

Answer 15

Introns, 3rd codon base and parts of the terminator region

Question 16

What is sequence conservation used for?

Answer 16

Cross species comparison and conservation

Question 17

Why is cross species comparison important?

Answer 17

To generate an evolutionary profile for a gene or gene family

Question 18

Why is cross species conservation important?

Answer 18

Allows us to identify important gene regions and allows us to concentrate on areas that are important in novel genes

Question 19

What is the main aim of a phylogenetic tree?

Answer 19

To illustrate the relatedness of different species/ strains/ sequences

Question 20

What determines the distance between two things on a phylogenetic tree?

Answer 20

How similar they are

Question 21

How is time estimated on a phylogenetic tree?

Answer 21

By measuring mutation rates

Question 22

What is gene duplication generally caused by?

Answer 22

Unequal crossing over during meiosis

Question 23

What happens to the genes after gene duplication has taken place?

Answer 23

One continues the original function, but the other evolves new functions through changes in the coding and/or control sequences

Question 24

What is unequal crossing over?

Answer 24

Recombination between sequences that are not the correct sequence but are very similar

Question 25

What are the two clusters of globin genes?

Answer 25

Alpha-like and beta-like

Question 26

Where are the alpha-like globin clusters found and what are they made up of?

Answer 26

Chromosome 16 - 3 genes and 3 pseudogenes

Question 27

Where are the beta-like globin clusters found and what are they made up of?

Answer 27

Chromosome 11 - 5 genes and 1 pseudogene

Question 28

What are the genes on the globin gene clusters arranged in order of?

Answer 28

Expression during development

Question 29

What has divergence of promoters allowed on the globin gene clusters?

Answer 29

They bind different transcription factors and allow the expression of genes at different stages of development

Question 30

What are pseudogenes?

Answer 30

Non-functioning genes that look similar to functioning genes

Question 31

How do pseudogenes come about?

Answer 31

Through many mutations

Question 32

When does sickle cell anaemia normally present?

Answer 32

5-6 months of age

Question 33

What are the main symptoms of sickle cell disease?

Answer 33

Anaemia, acute pain episodes, increased infection frequency

Question 34

What are the less common symptoms of sickle cell disease?

Answer 34

``` Stroke Pulmonary hypertension Gallstones Liver and kidney problems Joint problems Delayed puberty ```

Question 35

What causes sickle cell anaemia?

Answer 35

A single base substitution in the beta globin gene from GAG -> GTG

Question 36

Where does the substitution for sickle cell anaemia take place and what amino acids change?

Answer 36

Position 7 of the protein- glutamine -> valine

Question 37

What type of genetic disease is sickle cell disease?

Answer 37

Autosomal recessive

Question 38

Where is sickle cell disease common?

Answer 38

African, Mediterranean, Middle Eastern and Indian populations

Question 39

Why is sickle cell disease still common in some parts of the world?

Answer 39

One HbS variant confers resistance to severe malaria