Final answer:
The amount of ATP stored in a muscle cell can sustain activity for only 1-4 seconds. After that, the muscle uses creatine phosphate and anaerobic glycolysis for short bursts of energy, and aerobic respiration for sustained energy production.
Step-by-step explanation:
The amount of ATP stored in a muscle cell can keep a muscle active for about C) 1-4 seconds. ATP, or adenosine triphosphate, is the energy currency of the cell and is essential for muscle contractions. In muscle cells, ATP must be regenerated quickly through various mechanisms because the store of ATP is quite low, supporting only a few seconds of contraction. After the initial ATP is used, creatine phosphate metabolism takes over, providing energy for about 15 seconds. Subsequently, anaerobic glycolysis generates ATP from glycogen, which supplies energy for up to 90 seconds in the absence of oxygen, producing pyruvic acid that may convert to lactic acid during strenuous exercise. For longer or less intense activity, aerobic respiration is the primary source of ATP and occurs in the mitochondria using oxygen.
Muscle cells have a small amount of ATP stored within them that can be immediately used, but this ATP can only last for about 3 seconds. Once muscle contraction begins, the production of more ATP needs to start quickly. There are three mechanisms by which ATP can be regenerated: creatine phosphate metabolism, anaerobic glycolysis, and aerobic respiration. Creatine phosphate can supply energy for about 15 seconds, but the total amount of ATP stored in a muscle cell can power the muscle for approximately 1-4 seconds.