How does ATP participate in energy-coupling reactions?

• A. Hydrolysis of ATP fuels endergonic reactions.
• B. Hydrolysis of ADP fuels endergonic reactions.
• C. Synthesis of ATP fuels exergonic reactions.
• D. Synthesis of ADP fuels exergonic reactions.

Answer: (A)

Verified step by step guidance

1. Understand the concept of energy-coupling: Energy-coupling in cells involves using energy released from exergonic reactions to drive endergonic reactions. ATP (adenosine triphosphate) plays a crucial role in this process.
2. Learn about ATP hydrolysis: ATP hydrolysis is the process where ATP is broken down into ADP (adenosine diphosphate) and an inorganic phosphate (Pi), releasing energy. This reaction is exergonic, meaning it releases energy.
3. Connect ATP hydrolysis to endergonic reactions: The energy released from ATP hydrolysis is used to drive endergonic reactions, which are reactions that require an input of energy to proceed. This is how ATP participates in energy-coupling.
4. Differentiate between ATP and ADP: While ATP hydrolysis releases energy, the synthesis of ATP from ADP and Pi requires energy input, making it an endergonic process. Conversely, the synthesis of ADP from AMP (adenosine monophosphate) is not typically involved in energy-coupling.
5. Identify the correct statement: Based on the understanding of ATP's role in energy-coupling, the correct statement is that the hydrolysis of ATP fuels endergonic reactions, as it provides the necessary energy for these reactions to occur.