Physiology, Adenosine Triphosphate

Excerpt

The body is a complex organism, and as such, it takes energy to maintain proper functioning. Adenosine triphosphate (ATP) is the primary energy source for cellular energy use and storage. The structure of ATP is a nucleoside triphosphate, consisting of a nitrogenous base (adenine), a ribose sugar, and 3 serially bonded phosphate groups. ATP is commonly referred to as the "energy currency" of the cell, as it provides readily releasable energy in the bond between the second and third phosphate groups. In addition to providing energy, ATP hydrolysis supports a broad range of cellular functions, including signaling and DNA/RNA synthesis. ATP synthesis utilizes energy obtained from multiple catabolic mechanisms, including cellular respiration, beta-oxidation, and ketosis.

The majority of ATP synthesis occurs during cellular respiration in the mitochondrial matrix, generating approximately 32 ATP molecules per glucose molecule oxidized. ATP is consumed for energy in processes including ion transport, muscle contraction, nerve impulse propagation, substrate phosphorylation, and chemical synthesis. These processes, among others, create a high demand for ATP. As a result, cells in the human body depend on the hydrolysis of 100-150 moles of ATP per day to ensure proper functioning. In the following sections, ATP is further evaluated for its role as a central molecule in cellular function.