Question

which mutation would allow the cell to pass the g1 checkpoint when it should not?
multiple choice
a mutation in rb, preventing it from dissociating with e2f
a mutation in rb, preventing it from associating with e2f
a mutation in cyclin, preventing it from associating with cdk
a mutation in cdk, preventing it from phosphorylating rb
a mutation in rb, preventing it from becoming phosphorylated

Explanation:

Normally, Rb protein binds to E2F transcription factor and inhibits cell - cycle progression. When Rb is phosphorylated by CDK - cyclin complex, it dissociates from E2F, allowing E2F to activate genes for cell - cycle progression. A mutation in Rb that prevents it from associating with E2F would mean E2F is always active and the cell may pass the G1 checkpoint inappropriately.

Answer:

B. A mutation in Rb, preventing it from associating with E2F