Question

what is the p53 gene and how can its mutation cause cancer?
○ it is a tumor suppressor gene that normally promotes dna synthesis, and which causes cancer when it fails identify damaged or mutated dna.
○ it is a tumor suppressor gene that normally promotes onset of cell division, and which causes cancer when it properly regulate cell division.
○ it is a proto - oncogene that normally promotes onset of cell division, and which causes cancer when it cannot off and always promotes cell division.
○ it is a proto - oncogene that normally promotes apoptosis, and which causes cancer when it induces apoptosis healthy cells but not in irregularly dividing cells.
○ it is a tumor suppressor gene that normally promotes apoptosis, and which causes cancer when it fails to ind apoptosis in rapidly dividing cells.

Explanation:

The p53 gene is a tumor - suppressor gene. Its normal function is to promote apoptosis (programmed cell death). When there are cells with damaged DNA or cells that are dividing in an irregular (rapid and unregulated) way, p53 should induce apoptosis. If p53 is mutated and fails to do this, these abnormal cells can continue to divide and form a tumor (cancer).

• The first option is wrong because p53 does not promote DNA synthesis.
• The second option is wrong because p53 does not promote the onset of cell division.
• The third option is wrong because p53 is not a proto - oncogene (proto - oncogenes promote cell division, while tumor - suppressor genes like p53 inhibit uncontrolled cell growth).
• The fourth option is wrong because p53 is not a proto - oncogene and its normal function is not to promote apoptosis in healthy cells in a way that is selective against irregularly dividing cells (its role is more about responding to abnormal cell conditions).

Answer:

It is a tumor suppressor gene that normally promotes apoptosis, and which causes cancer when it fails to induce apoptosis in rapidly dividing cells.