Energy utilization
Energy utilization is the use of chemical energy by an organism to power maintenance, movement, growth, reproduction, and other biological processes.
Cellular respiration: A set of metabolic pathways that extracts energy from molecules and makes it available to cells, chiefly as ATP. It releases energy from fuel molecules that organisms can spend on cellular work.
Basal metabolic rate: The rate of energy expenditure by an awake, resting organism under specified conditions. It estimates the minimum energy cost of maintaining basic bodily functions.
Locomotion: The active movement of an organism from one place to another. Muscle contraction and other movement mechanisms consume chemical energy.
Fermentation: A metabolic pathway that regenerates NAD+ without an electron transport chain, yielding ATP through substrate-level phosphorylation. It supports ATP production when respiration is unavailable or oxygen is absent.
Energy budget: An accounting of energy entering an organism and its allocation among maintenance, activity, growth, and reproduction. It makes the competing costs of biological processes explicit.
Adenosine triphosphate: A nucleotide that transfers usable chemical energy and phosphate groups in cells. ATP directly couples energy-releasing reactions to energy-demanding cellular processes.
ATP hydrolysis: The reaction that breaks ATP into ADP and phosphate, releasing free energy under cellular conditions. Its free-energy change helps power transport, synthesis, and mechanical work.
Thermoregulation: The control of body temperature within a range compatible with physiological function. Maintaining temperature can account for substantial energy expenditure in animals.
Anaerobic respiration: Respiration that uses an electron transport chain with a terminal electron acceptor other than oxygen. It sustains energy extraction in organisms and environments where oxygen is absent.
Starvation: A prolonged shortage of nutrients that forces an organism to draw on stored reserves and body tissues. When intake cannot meet demand, organisms alter or sacrifice energy-consuming functions.