[Campbell Biology P.445] A normal cell undergoes a mutation that leads to the overproduction... | Practice Question

A normal cell undergoes a mutation that leads to the overproduction of a protein similar to Ras, causing uncontrolled cell division. Subsequently, a second mutation occurs, rendering a protein similar to p53 nonfunctional. What is the most likely consequence of these two sequential mutations in the cell?

  • A: The cell's growth will be inhibited due to the p53 mutation, counteracting the Ras-like protein effect.
  • B: The cell will likely exhibit significantly enhanced cancerous characteristics due to both stimulating and inhibiting growth controls being disrupted.
  • C: The cell will revert to normal cell cycle control because the p53 mutation will override the Ras-like protein's effect.
  • D: The cell will undergo programmed cell death (apoptosis) due to the accumulated genetic damage.

Explanation

Overactive Ras a proto-oncogene product stimulates cell division, acting like an 'accelerator'. Nonfunctional p53 a tumor-suppressor product means the cell loses its 'brake' on abnormal cell division and its ability to trigger apoptosis or repair DNA in response to damage. The combination of an overactive growth stimulator and a non-functional growth inhibitor/DNA repair protein is a classic scenario for highly aggressive cancerous growth, as the cell can both excessively divide and accumulate further mutations without control.