1 Explain why cells with defects in thymidine kinase grow in

1. Explain why cells with defects in thymidine kinase grow in media containing high amounts of 5-bromodeoxyuridine [BrdU], whereas cells with normal thymidine kinase will die when exposed to BrdU?

A. Without thymidine kinase, the BrdU is phosphorylated by Dihydrofolate Reductase and inactivated.

B.Thymidine kinase is required for the thymidylate synthase reaction to work.

C. When thymidine kinase is lacking, BrdU does not become phosphorylated and hence cannot be incorporated into DNA.

D. When thymidine kinase is not present, protein phosphatase dephosphorylates BrdU preventing its incorporation into RNA

Solution

Answer:

Correct answer is c) when thymidine kinase is lacking, BrdU does not become phosphorylated and hence cannot be incorporated into DNA,
Explanation: BrdU is used as a thymidine analog for selecting cells that have defective thymidine kinase. Thymidine kinase phospohrylates BrdU, whichn upon phosphorylation gets incorporated into DNA and causes cell death.