L3

Question 1

What are the three main types of repetitive DNA sequences?

Answer 1

1. Microsatellites: 2-3 nucleotides are repeated
2. Short tandem repeats (STRs): 2-9 nucleotides repeated
3. Variable number tandem repeats (VNTRs): 10+ repeats

Question 2

SSLPs - replication slippage

Answer 2

• Repetitive DNA sequences are “hotspots” for polymorphisms because they confuse the replication machinery of a cell, like typos
• SSLPs are caused by DNA replication error called replication slippage or slipped-strand mispairing

Question 3

SSLPs Insertion

Answer 3

• Addition of repeats

- Slippage of the daughter strand

Question 4

SSLPs Deletion

Answer 4

• Removal of repeats

- Slippage of the template strand

Question 5

What are INDELs?

Answer 5

• Insertion or deletion of 1 to a few nucleotides, NOT repetitive DNA

Question 6

What are copy number variations?

Answer 6

• Genomes can differ in the number of copies of parts of individual genes, or sets of genes
• CNVs include gene duplications that increase copy number, and deletions that reduce copy number
• Gene copies can be side by side, far away on the chromosome, or on a different chromosome