Genome variation Flashcards
What is a single nucleotide variant?
A base substitution
Where are a majority of SNVs not present in?
Majority not in exone
What are SNVs generated by and when?
Generated by mismatch repair during DNA replication
Its when the repair system process goes wrong
What does Bi-allelic mean?
When there is a possibility for 2 alleles at one site
Where may SNVs be present?
- Genes
- Promoter
- Non-coding regions
What can SNVs in a gene cause?
- No amino acid change(Synonymous)
- Amino acid change(Non-synonymous)
- Stop codon(nonsense)
- Splice Sit
- UTR
What evolutionary forces influence SNVs?
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
What are point mutations?
When SNVs are pathogenic
What are micro-satellites?
Repeating units
What can microsatellites alter?
Alter the actual size of that region of the genome
How can microsatellites be described in terms of alleles?
Multi-allelic
Where can micro-satellites be present?
Can be anywhere in the genome
What are micro-satellites also known as?
Also known as short tandem repeats
What is polymerase slippage model?
An error in DNA replication
Steps involved in polymerase slippage model?
- Polymerase pauses to check sequence is correct
- Causes growing sequence to dettach
- However when you have a repetitive sequence, annealing with subsequent bases can occur, resulting in the formation of a bubble
- Then the DNA mismatch repair mechanism realigns the template strand and bubble is straightened out
- Thus causing the double helix being expanded
