Chapter 6 Terms Flashcards
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)
Kilocalories (kcal)
A quantity of heat equal to 1,000 calories. Used to measure the energy content of food, it is usually called a “Calorie”
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 that can accept electrons during the redox reactions of cellular metabolism. The plus sign indicates that the molecule is oxidized and ready to pick up hydrogens; the reduced, hydrogen - (electron -) carrying form is NADH
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
Glycolysis
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 second major stage of cellular respiration
Oxidative Phosphorylation
The production of ATP using energy derived from the redox reactions of an electron transport chain; the third major stage of cellular respiration
Chemiosmosis
Energy-coupling mechanics that uses the energy of hydrogen ions (H+) gradients across membranes to phosphorylate ADP; powers most ATP synthesis in cells
ATP Synthase
A cluster of several membrane proteins that function in chemiosmosis with adjacent electron transport chains, using the energy of a hydrogen ion concentration gradient to make ATP
Substrate-Level Phosphorylation
The formation of ATP by an enzyme directly transferring a phosphate group to ADP from an organic molecule (for example, one of the intermediates in glycolysis or the citric acid cycle)
Intermediate
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
