Which compound donates a phosphate in the ATP-PC system?

Which compound donates a phosphate in the ATP-PC system?

• A. Adenosine diphosphate
• B. Creatine phosphate
• C. Glucose
• D. Adenosine triphosphate

Answer: (B)

In the ATP-PC system, the quick source of energy relies on a phosphate store called phosphocreatine (creatine phosphate). It donates its phosphate to ADP to rapidly regenerate ATP, with the help of the enzyme creatine kinase. The key reaction is phosphocreatine plus ADP forming ATP and creatine. This allows a rapid spike in ATP production to meet immediate high-intensity demands, but stores are limited, so this system supports only short bursts. The other substances don’t act as the phosphate donor here: adenosine diphosphate is the recipient, glucose feeds energy through glycolysis, and ATP isn’t the donor in this rapid phosphagen pathway.

In the ATP-PC system, the quick source of energy relies on a phosphate store called phosphocreatine (creatine phosphate). It donates its phosphate to ADP to rapidly regenerate ATP, with the help of the enzyme creatine kinase. The key reaction is phosphocreatine plus ADP forming ATP and creatine. This allows a rapid spike in ATP production to meet immediate high-intensity demands, but stores are limited, so this system supports only short bursts. The other substances don’t act as the phosphate donor here: adenosine diphosphate is the recipient, glucose feeds energy through glycolysis, and ATP isn’t the donor in this rapid phosphagen pathway.