1. Active site
    The part of an enzyme molecule where a substrate molecule attaches (by means of weak chemical bonds); typically, a pocket or groove on the enzyme's surface.
  2. active transport
    The movement of a substance across a biological membrane against its concentration gradient, aided by specific transport proteins and requiring input of energy (often as ATP).
  3. adenosine triphosphate (ATP)
    Main energy source for cells.
  4. aquaporin
    A transport protein in the plasma membrane of some plant or animal cells that facilitates the diffusion of water across the membrane
  5. cellular respiration
    The aerobic harvesting of energy from food molecules; the energy-releasing chemical breakdown of food molecules, such as glucose, and the storage of potential energy in a form that cells can use to perform work; involves glycolysis, the citric acid cycle, and oxidative phosphorylation (the electron transport chain and chemiosmosis).
  6. chemical energy
    Energy available in molecules for release in a chemical reaction; a form of potential energy.
  7. coenzyme
    An organic molecule serving as a cofactor. Most vitamins function as coenzymes in important metabolic reactions.
  8. cofactor
    A nonprotein molecule or ion that is required for the proper functioning of an enzyme. See also coenzyme.
  9. competitive inhibitor
    A substance that reduces the activity of an enzyme by binding to the enzyme's active site in place of the substrate. A competitive inhibitor's structure mimics that of the enzyme's substrate.
  10. concentration gradient
    An increase or decrease in the density of a chemical substance in an area. Cells often maintain concentration gradients of ions across their membranes.
Card Set
bio terms for ch. 5