[Campbell Biology P.209] Based on the text, what is the regulatory role of ATP and ADP on ca... | Practice Question

Based on the text, what is the regulatory role of ATP and ADP on catabolic enzymes, and what is the metabolic rationale behind this regulation?

  • A: ATP activates catabolic enzymes when energy is high; ADP inhibits them when energy is low.
  • B: ATP inhibits catabolic enzymes to slow down ATP production when energy is sufficient; ADP activates them to speed up ATP production when energy is low.
  • C: Both ATP and ADP inhibit catabolic enzymes to prevent overproduction of energy.
  • D: Both ATP and ADP activate catabolic enzymes to ensure constant energy supply.

Explanation

The text states: 'ATP binds to several catabolic enzymes allosterically, lowering their affinity for substrate and thus inhibiting their activity. ADP, however, functions as an activator of the same enzymes. This is logical because catabolism functions in regenerating ATP. If ATP production lags behind its use, ADP accumulates and activates the enzymes that speed up catabolism, producing more ATP. If the supply of ATP exceeds demand, then catabolism slows down as ATP molecules accumulate and bind to the same enzymes, inhibiting them.'