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.
A catabolic pathway that consumes oxygen (O2) and organic molecules, 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 conversion of pyruvate to carbon dioxide and ethyl alcohol.
A metabolic pathway that consumes energy to synthesize a complex molecule from simpler compounds.
The use of inorganic molecules other than oxygen to accept electrons at the "downhill" end of electron transport chains.
A complex of several membrane proteins that provide a port through which protons diffuse. This complex functions in chemiosmosis with adjacent electron transport chains, using the energy of a hydrogen ion (proton) concentration gradient to make ATP.
A metabolic sequence that breaks fatty acids down to two-carbon fragments that enter the citric acid cycle as acetyl CoA.
A metabolic pathway that releases energy by breaking down complex molecules to simpler compounds.
The catabolic pathways of aerobic and anaerobic respiration, which break down organic molecules 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
citric acid cycle
A chemical cycle involving eight steps that completes the metabolic breakdown of glucose molecules begun in glycolysis by oxidizing pyruvate to carbon dioxide; occurs within the mitochondrion in eukaryotic cells and in the cytosol of prokaryotes; the second major stage in cellular respiration.
An iron-containing protein that is a component of electron transport chains in the mitochondria and chloroplasts of eukaryotic cells and the plasma membranes of prokaryotic cells.
electron transport chain
A sequence of electron carrier molecules (membrane proteins) that shuttle electrons during the redox reactions that release energy used to make ATP.
An organism that makes ATP by aerobic respiration if oxygen is present but that switches to anaerobic respiration or fermentation if oxygen is not present.
A catabolic process that makes a limited amount of ATP from glucose without an electron transport chain and that produces a characteristic end product, such as ethyl alcohol or lactic acid
lactic acid fermentation
Glycolysis followed by the conversion of pyruvate to lactate, with no release of carbon dioxide
A coenzyme that can accept an electron and acts as an electron carrier in the electron transport chain.
An organism that only carries out fermentation or anaerobic respiration. Such organisms cannot use oxygen and in fact may be poisoned by it.
The production of ATP using energy derived from the redox reactions of an electron transport chain; the third major stage of cellular respiration.
The potential energy stored in the form of An electrochemical gradient, generated by the pumping of hydrogen ions across a biological membrane during chemiosmosis.