An organism that makes ATP by aero- bic respiration if oxygen is present but that switches to anaerobic respiration or fermenta- tion if oxygen is not present.
A catabolic process that makes a limited amount of ATP from glucose (or other organic molecules) without an electron trans- port chain and that produces a characteristic end product, such as ethyl alcohol or lactic acid.
A series of reactions that ultimately splits glucose into pyruvate. Glycolysis occurs in almost all living cells, serving as the starting point for fermentation or cellular respiration.
Acetyl coenzyme A; the entry com- pound for the citric acid cycle in cellular respi- ration, formed from a two-carbon fragment of pyruvate attached to a coenzyme.
A catabolic pathway for organic molecules, using oxygen (O2) as the final electron acceptor in an electron trans- port chain and ultimately producing ATP. This is the most efficient catabolic pathway and is carried out in most eukaryotic cells and many prokaryotic organisms.
Glycolysis followed by the reduction of pyruvate to ethyl alcohol, regenerating NAD+ and releasing carbon dioxide.
A complex of several membrane proteins that functions in chemiosmosis with adjacent electron transport chains, using the energy of a hydrogen ion (proton) concentra- tion gradient to make ATP. ATP synthases are found in the inner mitochondrial membranes of eukaryotic cells and in the plasma mem- branes of prokaryotes.
The catabolic pathways of aerobic and anaerobic respiration, which break down organic molecules and use an electron transport chain for the production of ATP.
An energy- coupling mechanism that uses energy stored in the form of a hydrogen ion gradient across a membrane to drive cellular work, such as the synthesis of ATP. Under aerobic condi- tions, most ATP synthesis in cells occurs by chemiosmosis.
citric acid cycle
A chemical cycle involving eight steps that completes the metabolic breakdown of glucose molecules begun in gly- colysis by oxidizing acetyl CoA (derived from pyruvate) to carbon dioxide; occurs within the mitochondrion in eukaryotic cells and in the cytosol of prokaryotes; together with pyruvate oxidation, the second major stage in cellular respiration.