Key Terms

acetyl CoA

combination of an acetyl group derived from pyruvic acid and coenzyme A, which is made from pantothenic acid (a B-group vitamin)

aerobic respiration

process in which organisms convert energy in the presence of oxygen

anaerobic

process that does not use oxygen

anaerobic cellular respiration

process in which organisms convert energy for their use in the absence of oxygen

ATP synthase

(also, F1F0 ATP synthase) membrane-embedded protein complex that adds a phosphate to ADP with energy from protons diffusing through it

chemiosmosis

process in which there is a production of adenosine triphosphate (ATP) in cellular metabolism by the involvement of a proton gradient across a membrane

citric acid cycle

(also, Krebs cycle) series of enzyme-catalyzed chemical reactions of central importance in all living cells

dephosphorylation

removal of a phosphate group from a molecule

fermentation

process of regenerating NAD⁺ with either an inorganic or organic compound serving as the final electron acceptor; occurs in the absence of oxygen

GLUT protein

integral membrane protein that transports glucose

glycolysis

process of breaking glucose into two three-carbon molecules with the production of ATP and NADH

isomerase

enzyme that converts a molecule into its isomer

Krebs cycle

(also, citric acid cycle) alternate name for the citric acid cycle, named after Hans Krebs who first identified the steps in the pathway in the 1930s in pigeon flight muscles; see citric acid cycle

oxidative phosphorylation

production of ATP using the process of chemiosmosis and oxygen

phosphorylation

addition of a high-energy phosphate to a compound, usually a metabolic intermediate, a protein, or ADP

prosthetic group

(also, prosthetic cofactor) molecule bound to a protein that facilitates the function of the protein

pyruvate

three-carbon sugar that can be decarboxylated and oxidized to make acetyl CoA, which enters the citric acid cycle under aerobic conditions; the end product of glycolysis

redox reaction

chemical reaction that consists of the coupling of an oxidation reaction and a reduction reaction

substrate-level phosphorylation

production of ATP from ADP using the excess energy from a chemical reaction and a phosphate group from a reactant

TCA cycle

(also, citric acid cycle) alternate name for the citric acid cycle, named after the group name for citric acid, tricarboxylic acid (TCA); see citric acid cycle

ubiquinone

soluble electron transporter in the electron transport chain that connects the first or second complex to the third