[Campbell Biology P.433] Based on Figure 18.18, what would be the most likely outcome if a m... | Practice Question

Based on Figure 18.18, what would be the most likely outcome if a mutation in the myoD gene resulted in an altered MyoD protein that could not activate the myoD gene itself or other muscle-specific genes?

  • A: The embryonic precursor cell would still determine into a myoblast but fail to differentiate into a muscle fiber.
  • B: The embryonic precursor cell would be unable to commit to becoming a myoblast, and thus no skeletal muscle cells would form.
  • C: Myoblasts would form, but they would continue to divide indefinitely, preventing muscle fiber formation.
  • D: Only the production of myosin and actin would be affected, but the cells could still become functional muscle fibers.

Explanation

This question assesses the understanding of MyoD as a master regulatory gene and its critical role in both determination and differentiation. If MyoD cannot activate its own gene or other muscle-specific genes, the entire pathway of muscle cell development would be halted at its earliest stages, preventing the formation of myoblasts and subsequent muscle fibers.