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Multiple Choice
Which molecule helps regenerate ATP by donating a phosphate group during cellular respiration?
A
Pyruvate
B
Phosphocreatine
C
Glucose
D
NADH
Verified step by step guidance
1
Understand the role of ATP in cellular respiration: ATP (adenosine triphosphate) is the primary energy currency of the cell. It is regenerated from ADP (adenosine diphosphate) by the addition of a phosphate group.
Identify the molecules listed in the question and their roles: Pyruvate is a product of glycolysis, glucose is the starting molecule for glycolysis, NADH is an electron carrier, and phosphocreatine is involved in energy storage and transfer.
Recall the function of phosphocreatine: Phosphocreatine acts as a high-energy phosphate donor in cells, particularly in muscle cells, to regenerate ATP from ADP during periods of high energy demand.
Understand the mechanism: The enzyme creatine kinase catalyzes the transfer of a phosphate group from phosphocreatine to ADP, forming ATP. This process is part of the phosphagen system, which provides a rapid source of ATP.
Conclude that phosphocreatine is the molecule that directly donates a phosphate group to regenerate ATP during cellular respiration, especially in high-energy-demand situations.