| A | B |
|---|
| aerobic | containing oxygen; an organism, environment, or cellular process that requires oxygen |
| anaerobic | lacking oxygen; an organism, environment, or cellular process that lacks oxygen |
| 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 Krebs cycle, the electron transport chain , and chemiosmosis |
| redox reaction | 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. |
| oxidation | The loss of electrons from a substance involved in a redox reaction; always accompanies reduction |
| reduction | The gain of electrons by a substance involved in a redox reaction; always accompanies oxidation |
| dehydrogenase | An enzyme that catalyzes a chemical reaction during which one or more hydrogen atoms are removed from a molecule. |
| NAD+ | Nicotinamide adenine dinucleotide; a coenzyme present in all cells that assists enzymes by conveying electrons (hydrogen atoms) during the redox reactions of metabolism; the plus sign indicates that the molecule is oxidized and tends to pick up hydrogen atoms. |
| electron carrier | A molecule that conveys electrons; one of several membrane proteins in electron transport chains in cells. Electron carriers shuttle electrons during the redox reactions that release energy used to make ATP. |
| electron transport chains | A sequence of electron-carrier molecules (membrane proteins) that shuttle electrons during the redox reactions that release energy used to make ATP; located in the cristae of mitochondria |
| chemiosmosis | The production of ATP using the energy of hydrogen-ion gradients across membranes to phosphorylate ADP; powers most ATP synthesis in cells. |
| ATP synthases | A cluster of several membrane proteins found in the mitochondrial cristae (and bacterial plasma membrane) that function in chemiosmosis with adjacent electron transport chains, using the energy of a hydrogen-ion concentraition gradient to make ATP. ATP synthases provide a port through which hydrogen ions diffuse into the matrix of a mitochondrion. |
| substrate-level phosphorylation | The formation of ATP occurring when an enzyme transfers a phosphate group from an organic molecule to ADP. |
| glycolysis | The multistep chemical breakdown of a molecule of glucose into two molecules of pyruvic acid; the first stage of cellular respiration in all organsisms; occurs in the cytoplasmic fluid |
| Krebs cycle | The metabolic cycle that is fueled by acetyl CoA formed after glycolysis in cellular respiration; chemical reactions in the Krebs cycle complete the metabolic breakdown of glucose molecuels to carbon dioxide; occurs in the matrix of mitochondria and supplies most of the NADH molecules that carry energy to the electron transport chains. |
| intermediates | One of the compounds that form between the inital reactant in a metabolic pathway; such as glucose in glycolysis, and teh final product, such as pyruvic acid in glycolysis |
