Which statement best reflects the key points of the ATP/PC energy system?

Which statement best reflects the key points of the ATP/PC energy system?

• A. It is an aerobic process
• B. The controlling enzyme is creatine kinase
• C. It breaks down phosphocreatine into phosphate and ADP
• D. It releases energy to make three ATP molecules

Answer: (B)

The ATP/PC energy system provides immediate, anaerobic energy by rapidly resynthesizing ATP from adenosine diphosphate using the phosphate from phosphocreatine. The crucial point is the enzyme that controls how fast this happens: creatine kinase catalyzes the transfer of a phosphate from phosphocreatine to ADP to form ATP (and creatine). This enzyme sets the pace for the system, which is why identifying its role makes the statement the best fit. The system is not aerobic and does not create three ATP per phosphocreatine molecule; it typically yields one ATP per PCr, and the phosphocreatine breakdown releases inorganic phosphate as part of the process.

The ATP/PC energy system provides immediate, anaerobic energy by rapidly resynthesizing ATP from adenosine diphosphate using the phosphate from phosphocreatine. The crucial point is the enzyme that controls how fast this happens: creatine kinase catalyzes the transfer of a phosphate from phosphocreatine to ADP to form ATP (and creatine). This enzyme sets the pace for the system, which is why identifying its role makes the statement the best fit. The system is not aerobic and does not create three ATP per phosphocreatine molecule; it typically yields one ATP per PCr, and the phosphocreatine breakdown releases inorganic phosphate as part of the process.