[Campbell Biology P.279] Considering the role of Ced-9 as a master regulator of apoptosis in... | Practice Question

Considering the role of Ced-9 as a master regulator of apoptosis in C. elegans , what would be the most likely consequence if a C. elegans strain had a genetic mutation causing its Ced-9 protein to be constitutively always inactive?

  • A: Apoptosis would be completely inhibited, leading to the survival of all cells regardless of internal or external signals.
  • B: The cell would be unable to receive any death-signaling molecules, thus remaining alive.
  • C: Apoptosis would proceed constitutively or be overly sensitive to activation, likely leading to excessive and inappropriate cell death.
  • D: Ced-3 and Ced-4 proteins would be synthesized in an active form, bypassing the need for Ced-9.

Explanation

Ced-9 normally acts as a 'brake' on apoptosis by inhibiting Ced-4. If Ced-9 is constitutively inactive, this inhibition is removed, allowing Ced-4 to activate Ced-3 and initiate the apoptotic cascade without proper regulation, leading to excessive and unintended cell death.