Question

During the G1 checkpoint, p53 binds DNA and acts as a transcriptional activator of the ______ ______ ______

Answer 1

p53 acts as a transcriptional activator for the p21 gene at the G1 checkpoint, halting the cell cycle in response to DNA damage and triggering repair or apoptosis to prevent cancerous cell division.

Step-by-step explanation:

During the G1 checkpoint, p53 binds DNA and acts as a transcriptional activator of the p21 gene, among others. The p53 protein plays a crucial role as a multifunctional regulator that responds to DNA damage in cells preparing for division. When DNA damage is detected, p53 stops the cell cycle and initiates DNA repair processes. If repair is not possible, p53 can induce apoptosis to prevent the replication of defective DNA. The increasing levels of p53 lead to the production of p21, which enforces the cell cycle arrest by inhibiting Cdk/cyclin complexes, thus preventing the progression into the S phase under stress conditions. This mechanism ensures that only healthy cells without DNA damage will continue to divide, acting as an important safeguard against the potential development of cancerous cells.