The ATP formed as part of respiration

The ATP formed as part of respiration is used in a wide variety of contexts in biology. For example in order for an animal to move and hunt for food within its environment, it has to contract its muscle tissue. The tissue is composed of cells containing actin and myosin filaments which move relative to each other to contract a sarcomere. For this to happen, actomyosin cross-bridges form between the actin and myosin. Once activated by calcium ions, the enzyme ATPase then hydrolyses ATP to ADP and Pi releasing energy for the detachment and formation of more cross-bridges, giving rise to the sliding filament theory of muscle contraction. This enzyme also helps release energy from ATP in a wide variety of contexts, such as in the active transport of sodium ions out of an axon through sodium-potassium cation pump in the generation of a resting potential, or in the active transport of nitrate ions into a root hair cell to lower water potential to draw in water to generate a root pressure.