Final answer:
ATP is the primary energy currency in cells, storing energy in the phosphate bonds. ATP can be created through oxidative phosphorylation, substrate-level phosphorylation, and photophosphorylation, with different locations and amounts of ATP produced in each process. Two reactions that use ATP in cells include muscle contraction and active transport. Fermentation is different from cellular respiration in terms of ATP production, and organisms carry out fermentation when oxygen is lacking.
Step-by-step explanation:
ATP (adenosine triphosphate) is the primary energy currency in cells. The energy in ATP is stored in the phosphate bonds between the three phosphate groups. When ATP is used for energy, a phosphate group is detached, converting ATP to ADP (adenosine diphosphate) and releasing energy.
Oxidative phosphorylation, substrate-level phosphorylation, and photophosphorylation are the three major processes through which ATP is created. Oxidative phosphorylation takes place in the mitochondria, while substrate-level phosphorylation occurs in the cytoplasm. Photophosphorylation occurs during the light reactions of photosynthesis. Oxidative phosphorylation creates the most ATP, followed by substrate-level phosphorylation and then photophosphorylation.
Two reactions or processes in cells that use ATP include muscle contraction and active transport. Muscle contraction requires ATP to power the movement of muscle fibers, while active transport uses ATP to move molecules against their concentration gradient.
Fermentation is different from cellular respiration in terms of ATP production. Fermentation is an anaerobic process that occurs when oxygen is scarce. It produces a small amount of ATP through glycolysis alone. Cellular respiration, on the other hand, is an aerobic process that occurs in the presence of oxygen. It produces a large amount of ATP through the processes of glycolysis, the citric acid cycle, and oxidative phosphorylation. Organisms carry out fermentation when oxygen is not available as a way to continue producing some ATP for basic cellular functions.