Question

The p53 protein is primarily known for which cellular role?

• A. DNA replication
• B. Tumor suppression
• C. Protein synthesis
• D. Cell membrane transport

Hint:

p53 protein → “Guardian of the genome” → Prevents cancer by stopping damaged cells from dividing

Answer 1

The Correct Option is B

This question is about a critical protein in cell biology and cancer research. The p53 protein acts as a central hub in a network of signaling pathways that protect the cell from various stresses, particularly those that can damage DNA and lead to cancer. Its role is so fundamental that it is often called the "guardian of the genome."
Understanding the Question The question asks for the main, well-established function of the p53 protein within a cell.
Key Concepts and Approach The key concepts are cell cycle control, DNA repair, and apoptosis (programmed cell death). The approach is to describe how p53 responds to cellular damage and how this response prevents cancer.
Detailed Solution
Response to Cellular Stress: The p53 protein is activated when a cell experiences stress, most notably DNA damage (e.g., from UV radiation or chemical mutagens).
Key Functions of Activated p53: Once activated, p53 acts as a transcription factor, initiating one of two main pathways:
Cell Cycle Arrest: It can halt the cell division cycle, providing the cell with time to repair the damaged DNA before it can be replicated.
Apoptosis: If the DNA damage is too severe to be repaired, p53 can trigger apoptosis, or programmed cell death. This eliminates the damaged cell, preventing it from passing on mutations.

The Result: Tumor Suppression: By preventing cells with damaged DNA from proliferating, p53 effectively stops the development of tumors at an early stage. This is why the gene encoding p53 is the most frequently mutated gene in human cancers.