[Campbell Biology P.438] The p53 gene is a critical tumor-suppressor gene. Given its functio... | Practice Question

The p53 gene is a critical tumor-suppressor gene. Given its function as a transcription factor promoting cell cycle-inhibiting proteins, what is the most significant consequence if a cell has a mutation that 'knocks out' its p53 gene?

  • A: The cell will immediately undergo apoptosis, preventing tumor formation.
  • B: The cell will continue its cell cycle despite DNA damage, accumulating further mutations and potentially forming a tumor.
  • C: The cell will become hyper-responsive to external growth factors, speeding up its division rate.
  • D: The cell's ability to repair DNA will be significantly enhanced, preventing any further mutations.

Explanation

The text explains that the p53 protein 'promotes the synthesis of cell cycle-inhibiting proteins' and that 'operation of this signaling pathway blocks the cell cycle until the damage has been repaired.' Therefore, a mutation that 'knocks out' the p53 gene would prevent this cell cycle arrest, allowing damaged cells to proliferate and accumulate further mutations, thus contributing to tumor formation.