Genome variation

Question 1

What is a single nucleotide variant?

Answer 1

A base substitution

Question 2

Where are a majority of SNVs not present in?

Answer 2

Majority not in exone

Question 3

What are SNVs generated by and when?

Answer 3

Generated by mismatch repair during DNA replication

Its when the repair system process goes wrong

Question 4

What does Bi-allelic mean?

Answer 4

When there is a possibility for 2 alleles at one site

Question 5

Where may SNVs be present?

Answer 5

• Genes
• Promoter
• Non-coding regions

Question 6

What can SNVs in a gene cause?

Answer 6

• No amino acid change(Synonymous)
• Amino acid change(Non-synonymous)
• Stop codon(nonsense)
• Splice Sit
• UTR

Question 7

What evolutionary forces influence SNVs?

Answer 7

Mutations
-Cause new alleles to arise, and we now have a variant
Gene flow
-Migration leading to introduction of that variant into another population
Genetic drift
-Random change in variant allele frequency between generations
Selections
-Non-random change in varrient allele frequency betweem generations because presence of one allele/genotype is pathogenic

Question 8

What are point mutations?

Answer 8

When SNVs are pathogenic

Question 9

What are micro-satellites?

Answer 9

Repeating units

Question 10

What can microsatellites alter?

Answer 10

Alter the actual size of that region of the genome

Question 11

How can microsatellites be described in terms of alleles?

Answer 11

Multi-allelic

Question 12

Where can micro-satellites be present?

Answer 12

Can be anywhere in the genome

Question 13

What are micro-satellites also known as?

Answer 13

Also known as short tandem repeats

Question 14

What is polymerase slippage model?

Answer 14

An error in DNA replication

Question 15

Steps involved in polymerase slippage model?

Answer 15

1. Polymerase pauses to check sequence is correct
2. Causes growing sequence to dettach
3. However when you have a repetitive sequence, annealing with subsequent bases can occur, resulting in the formation of a bubble
4. Then the DNA mismatch repair mechanism realigns the template strand and bubble is straightened out
5. Thus causing the double helix being expanded

Question 16

What is a copy number variation?

Answer 16

A variation in the number of copies between people

Question 17

What is the simplest type of copy number variation?

Answer 17

Simplest type is the presence or absence of a gene

Question 18

What can copy number variation be?

Answer 18

May be intergenic

Question 19

What is the mechanism by which copy number variation occurs?

Answer 19

Non-allele homologous recombination in meiosis

• Allele recombination is good
• But non-allele recombination in duplication/deletion and copy number change
  - Driven by regions of high sequence similarity

Question 20

What are variant effects used as?

Answer 20

Variant effects are used as markers to help find disease causing genes and mutation