Final answer:
ATP is the primary energy currency of cells, storing energy in its phosphoanhydride bonds that is released when converted to ADP and Pi. This energy is used to drive various cellular processes and is produced during the oxidation of nutrients in cellular respiration.
Step-by-step explanation:
Adenosine triphosphate, or ATP, functions as the primary energy currency in cells, capturing and transferring the energy released from exergonic reactions. When a fuel molecule from food is oxidized, the energy within its chemical bonds is used to convert adenosine diphosphate (ADP) and an inorganic phosphate group (Pi) into ATP. The bonds that store this energy in ATP are known as phosphoanhydride bonds. Upon hydrolysis, when ATP is converted back to ADP and Pi, this stored energy is released and made available for cellular processes, such as the synthesis of biomolecules, muscle contractions, and the transmission of nerve impulses. Within cells, the production of ATP through cellular respiration involves a series of metabolic reactions in the cytoplasm and mitochondria, where carbohydrates, proteins, and fats undergo oxidation to generate ATP. For example, glycolysis is a process in which glucose is converted into pyruvic acid while some of the chemical energy is captured in the form of NADH and ATP. The bond energy in ATP can then be harnessed in endergonic reactions, which require energy input, effectively coupling the release of energy from ATP with energy demands of various cellular reactions.