American Heritage
Medical Dictionary

cellular respiration n.
The series of metabolic processes by which living cells produce energy through the oxidation of organic substances.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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American Heritage
Science Dictionary
cellular respiration  
The process of cell catabolism in which cells turn food into usable energy in the form of ATP. In this process glucose is broken down in the presence of molecular oxygen into six molecules of carbon dioxide, and much of the energy released is preserved by turning ADP and free phosphate into ATP. Cellular respiration occurs as a series of chemical reactions catalyzed by enzymes, the first of which is glycolysis, a series of anaerobic reactions in which glucose (a 6-carbon molecule) is split into two molecules of lactate (a 3-carbon molecule), producing a net gain of two ATP molecules. In a series of aerobic reactions, lactate is converted to pyruvate, which enters the mitochondrion and combines with oxygen to form an acetyl group, releasing carbon dioxide. The acetyl group (CH3CO) is then combined with coenzyme A as acetyl coenzyme A, and enters the Krebs cycle. During this series of reactions, each acetyl group is oxidized to form two molecules of carbon dioxide, and the energy released is transferred to four electron carrier molecules. The electron carrier molecules then release their energy in a process that results in the pumping of protons (hydrogen ions) out across the inner membrane of the mitochondrion. The potential energy of the protons generated by one acetyl group is later released when they recross the membrane and are used to form three molecules of ATP from ADP and phosphate in the process of oxidative phosphorylation. The pyruvate from one molecule of glucose drives two turns of the Krebs cycle. Thus, during cellular respiration one molecule of glucose, as well as oxygen, ADP, and free phosphate are catabolized to yield six molecules of carbon dioxide and an increase in usable energy in the form of eight molecules of ATP.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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American Heritage
Cultural Dictionary

cellular respiration definition

The chemical process that generates most of the energy in the cell, supplying molecules needed to make the metabolic reactions (see metabolism) of an organism run.

Note: The main carrier of energy in metabolism is the molecule ATP.
The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Encyclopedia Britannica

cellular respiration

the process by which organisms combine oxygen with foodstuff molecules, diverting the chemical energy in these substances into life-sustaining processes and discarding, as waste products, carbon dioxide and water. Organisms that do not depend on oxygen degrade foodstuffs in a process called fermentation.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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Example sentences
The coral polyp then uses these products to grow and carry out cellular respiration.
The rates of both cellular respiration and photosynthesis would remain constant.
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