Answer: p53 (the guardian of the genome).
- A BRCA1 mainly, among tumour suppressors
- B p53 (the guardian of the genome)
- C Oncogenes such as RAS and MYC
- D APC mainly, among tumour suppressors
Correct answer: B. p53 (the guardian of the genome)
Explanation: p53 is a tumor suppressor protein. Mutated in >50% of human cancers. It normally stops cell cycle or triggers apoptosis when DNA is damaged.
The cell cycle: G1 (growth and preparation), S (DNA replication, chromosome number stays 2n but DNA content doubles), G2 (final checks before division), and M (mitosis itself) - together, G1+S+G2 make up interphase.
Concept context
Mitosis and meiosis: how cells divide for growth, repair, and reproduction.