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Glossary of Chapter 9 - Cellular Respiration: Harvesting Chemical Energy

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Fermentation
a partial degradation of sugars that occurs without the help of oxygen; an extension of glycolysis that can generate ATP solely by substrate-level phosphorylation – as long as there is a sufficient supply of NAD+ to accept electrons during the oxidation step of glycolysis
Cellular respiration
a process of energy harvest in which oxygen is consumed along with the energy source to produce ATP
Redox reactions
chemical reactions in which there is a transfer of one or more electrons from one reactant to another
Oxidation
the loss of an electron from a substance
Reduction
the gain of an electron by a substance
Reducing agent
the electron donor
Oxidizing agent
the electron acceptor
NAD+
nicotinamide adenine dinucleotide; a coenzyme that functions as an oxidizing agent during respiration
Glycolysis
the first stage of cellular respiration; occurs in the cytosol and begins the degradation of food molecules by breaking glucose into two molecules called pyruvate; literally means “splitting of the sugar”
Krebs cycle
the second stage of cellular respiration; occurs in the mitochondrial matrix; decomposes a derivative of pyruvate into carbon dioxide
ETC
the third stage of cellular respiration; accepts electrons from the breakdown products of the first two stages and passes the electrons from one molecule to another, all the way to molecular hydrogen and oxygen to form water
Oxidative phosphorylation
the process by which energy released in each step of the ETC is stored and used to make ATP; powered by the redox reactions that transfer electrons from food to oxygen; accounts for about 90% of the ATP produced by respiration
Substrate-level phosphorylation
a form of ATP synthesis that occurs when an enzyme transfers a phosphate group from a substrate to ADP; occurs during glycolysis and the Krebs cycle
Acetyl CoA
the molecule to which pyruvate is converted upon entering the mitochondrial matrix between the processes of glycolysis and the Krebs cycle
Cytochromes
an iron containing protein; a component of the ETC in both mitochondria and chloroplasts
ATP synthase
a protein complex that populates the interior of a mitochondrial membrane; the enzyme that actually makes ATP
Chemiosmosis
the coupling mechanism for oxidative phosphorylation; an H+ gradient couples the redox reactions of the electron transport chain to ATP synthesis
Proton-motive force
the H+ gradient that results from the ETC and that is used to drive the production of ATP
Alcohol fermentation
a type of fermentation; a process by which pyruvate is converted to ethanol
Lactic acid
a type of fermentation in which pyruvate is reduced directly by NADH to form lactate as a waste product, with no release of carbon dioxide
Beta metabolism
a process by which fatty acids are broken down into two carbon fragments before they enter the Krebs cycle as acetyl CoA

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