An enzyme that catalyzes a chemical reaction during which one or more hydrogen atoms are removed from a molecule.
Short for oxidation-reduction; a chemical reaction in which electrons are lost from one substance (oxidation) and added to another (reduction). Oxidation and reduction always occur together.
The loss of electrons from a substance involved in a redox reaction; always accompanies reduction.
The gain of electrons by a substance involved in a redox reaction; always accompanies oxidation.
electron transport chain
A series of electron carrier molecules that shuttle electrons during the redox reactions that release energy used to make ATP; located in the inner membrane of mitochondria, the thylakoid membranes of chloroplasts, and the plasma membranes of prokaryotes.
The multistep chemical breakdown of a molecule of glucose into two molecules of pyruvate; the first stage of cellular respiration in all organisms; occurs in the cytoplasmic fluid.
citric acid cycle
The metabolic cycle fueled by acetyl CoA formed after glycolysis in cellular respiration. Chemical reactions in the citric acid cycle complete the metabolic breakdown of glucose molecules to carbon dioxide. The cycle occurs in the matrix of mitochondria and supplies most of the NADH molecules that carry energy to the electron transport chains.
The production of ATP using energy derived from the redox reactions of an electron transport chain.
The production of ATP using the energy of hydrogen ion (H+) gradients across membranes to phosphorylate ADP; powers most ATP synthesis in cells.
A complex (cluster) of several proteins found in a cellular membrane (including the inner membrane of mitochondria, the thylakoid membrane of chloroplasts, and the plasma membrane of prokaryotes) that functions in chemiosmosis with adjacent electron transport chains, using the energy of a hydrogen ion concentration gradient to make ATP. An ATP synthase provides a port through which hydrogen ions (H+) diffuse.
The formation of ATP occurring when an enzyme transfers a phosphate group from an organic molecule (e.g., one of the intermediates in glycolysis or the citric acid cycle) to ADP.
One of the compounds that form between the initial reactant and the final product in a metabolic pathway, such as between glucose and pyruvate in glycolysis.
acetyl CoA (acetyl coenzyme A)
The entry compound for the citric acid cycle in cellular respiration; formed from a fragment of pyruvate attached to a coenzyme.
lactic acid fermentation
The conversion of pyruvate to lactate with no release of carbon dioxide.
The conversion of the acid produced by glycolysis to carbon dioxide and ethyl alcohol.
An organism that cannot survive in an atmosphere of oxygen.
A microorganism that makes ATP by aerobic respiration if oxygen is present, but that switches to fermentation when oxygen is absent.