Question

For the first step in fatty acid catabolism, we say that ATP is used to “drive” the reaction that links the fatty acid with coenzyme-A. Without ATP hydrolysis, would you predict that the linking of fatty acid to coenzyme-A would be ­exergonic or endergonic? In fatty acid CoA synthesis, the hydrolysis of the ATP portion is based on what major strategy of metabolism?

Accepted Answer

Understand the context: Fatty acid catabolism begins with the activation of the fatty acid by linking it to coenzyme-A (CoA). This reaction requires energy input, which is provided by ATP hydrolysis. The question asks whether this reaction would be exergonic (releases energy) or endergonic (requires energy) without ATP hydrolysis. Step 1: Recall the definition of endergonic and exergonic reactions. Endergonic reactions require an input of energy to proceed, while exergonic reactions release energy and occur spontaneously. Linking a fatty acid to CoA involves forming a high-energy thioester bond, which is not energetically favorable on its own. Step 2: Analyze the role of ATP hydrolysis. ATP hydrolysis provides the necessary energy to drive the reaction forward. The hydrolysis of ATP to ADP and inorganic phosphate (Pi) is highly exergonic, and this energy is coupled to the otherwise endergonic reaction of fatty acid-CoA formation. Step 3: Predict the reaction's nature without ATP hydrolysis. Without the energy provided by ATP hydrolysis, the reaction linking fatty acid to CoA would be endergonic because forming the high-energy thioester bond requires an input of energy. Step 4: Relate this to a major strategy of metabolism. The hydrolysis of ATP in this process is an example of energy coupling, a fundamental strategy in metabolism. Energy coupling uses the energy released from an exergonic reaction (like ATP hydrolysis) to drive an endergonic reaction (like fatty acid-CoA synthesis).

비슷한 문제에 대한 검증된 영상 답변:

주요 개념

Exergonic vs. Endergonic Reactions

ATP Hydrolysis

Metabolic Strategies