7-8: DNA Mutation and Repair

Question 1

In an auxotrophic yeast mutant requiring adenine, which stage of the adenine biosynthesis pathway would have to be mutated to produce a red pigment?

Answer 1

Enzyme 6

Question 2

What is the significance of the RAD9 gene?

Answer 2

Cells that have a deletion or mutation in Rad9 (i.e. rad9 mutants) fail to arrest at G2, even if they have sustained significant damage to their DNA

Question 3

How can UV affect DNA?

Answer 3

UV can be absorbed by aromatic rings of purine/pyrimidine bases, forming pyrimidine dimers, thus disrupting the double helix of DNA and preventing replication