W - BIOL200 - 3.6-3.8, REPAIR OF DNA MUTATIONS, REPAIR OF DOUBLE STRANDED DNA BREAKS, IN VITRO DNA REPLICATION: POLYMERIZATION CHAIN REACTION (PCR)

What are the 5 main types of mutations?

1. Silent

2. Missense

3. Nonsense

4. Insertion

5. Deletion

What do insertions/deletions often cause?

Frameshifts

Which mutations usually affect a single codon?

Silent, Missense, and Nonsense.

Which mutation does not change the protein?

 Silent mutation.

Which mutation changes one amino acid?

 Missense mutation.

Which mutation introduces a stop codon?

Nonsense mutation.

What is a tautomeric shift?

 Temporary rearrangement of electrons in bases.

What does tautomeric shift cause?

 Non-standard base pairing.

Example of tautomeric mispairing?

 T (enol) pairs with G instead of A.

Why are tautomeric shifts risky?

 They cause replication errors and mutations.

 What are germline mutations?

 Inherited mutations passed to offspring.

What are somatic mutations?

Acquired mutations not passed to offspring.

 What are spontaneous mutations?

Occur naturally, e.g. DNA replication errors.

What are induced mutations?

 Caused by mutagens (chemicals/radiation).

What is a loss-of-function mutation?

Gene product has reduced or no function.

What is a gain-of-function mutation?

New or increased activity of gene product.

Example of gain-of-function mutation?

Mutation that causes cancer (oncogenes).

What is a dominant-negative mutation?

Mutated protein interferes with normal protein.

What is a lethal mutation?

Causes death of the organism.

What is a conditional mutation?

Only expressed under certain conditions.

What is a temperature-sensitive mutation?

 Only affects function at high or low temps.

What is a suppressor mutation?

 A second mutation that restores function lost by a first.

What is intragenic suppression?

 Suppressor in the same gene as the first mutation.

What is intergenic suppression?

 Suppressor in a different gene.