Which molecule initiates the halt of the cycle when damaged dna is detected in g1? a. rbb. p53c. cdk/cyclin complexd. p21e. d2f

B. p53

Explanation:

It is p53 molecule which is primarily responsible for initiating halt of the cell cycle when damaged DNA is detected in G1 phase of cell cycle.

p53 is basically a tumor suppressor protein which participates in ATM signaling. ATM signaling comes into picture when a double stranded break is detected during G1 phase of cell cycle. ATM which is a kinase, uses phosphorylation as a mechanism to cause cell cycle arrest with the help of p53 and p21. In short, it acts as a cell cycle check point during G1 phase of cell cycle. Also, p53 is a transcription factor which helps in the synthesis of another protein known as p21 and p21 interacts with CDK (specifically CDK 4/6) and inhibits it which leads to cell cycle arrest.