cell cycle, apoptosis, and cancer

Question 1

What activating subunit does the Anaphase promoting complex (APC) require? and what type of job do they have

Answer 1

CDC20; they are a type of ubiquitin ligase which marks cyclins (via polyubiquitintaion) for destruction by a proteasome to regulate cyclin S & M activity

Question 2

what is the main function of DNA checkpoints in interphase (G1, S, G2) and mitosis?

Answer 2

to prevent entry of cells into the S phase as well as into mitosis when the DNA fails a integrity check – aka: DNA is damaged