Chapter 5: Key Terms Flashcards
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)
Active Transport
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
Active Site
Main energy source for cells
Adenosine Triphosphate
A transport protein in the plasma membrane of some plant or animal cells that
facilitates the diffusion of water across the membrane (osmosis)
Aquaporin
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)
Cellular Respiration
Energy available in molecules for release in a chemical reaction; a form of potential energy
Chemical Energy
An organic molecule serving as a cofactor. Most vitamins function as coenzymes in important metabolic reactions
Coenzyme
A nonprotein molecule or ion that is required for the proper functioning of an enzyme. See also coenzyme
Cofactor
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
Competitive Inhibitor
An increase or decrease in the density of a chemical substance in an area. Cells often maintain concentration gradients of ions across their membranes. When a gradient exists, substances tend to move from where they are more concentrated to where they are less concentrated
Concentration Gradient
The spontaneous tendency of a substance to move down its concentration gradient from where it is more concentrated to where it is less concentrated
Diffusion
An energy-requiring chemical reaction, which yields products with more potential energy than the reactants. The amount of energy stored in the products equals the difference between the potential energy in the reactants and that in the products
Endergonic Reaction
Cellular uptake of molecules or particles via formation of new vesicles from the plasma membrane
Endocytosis
The capacity to perform work, or to rearrange matter
Energy
In cellular metabolism, the use of energy released from an exergonic reaction to drive an endergonic reaction
Energy Coupling
A measure of disorder. One form of disorder is heat, which is random molecular motion
Entropy
A protein (or RNA molecule) that serves as a biological catalyst, changing the rate of a chemical reaction without itself being changed into a different molecule in the process
Enzyme
An energy-releasing chemical reaction in which the reactants contain more potential energy than the products. The reaction releases an amount of energy equal to the difference in potential energy between the reactants and the products
Exergonic Reaction
The movement of materials out of the cytoplasm of a cell by the fusion of vesicles with the plasma membrane
Exocytosis
The passage of a substance through a specific transport protein across a biological membrane down its concentration gradient
Facilitated Diffusion
A method of metabolic control in which a product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway
Feedback Inhibition
