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NAD+ reaction. The Kreb Cycle. (named in 1930 after Hans Kreb) Aka citric acid cycle tricarboxylic acid cycle. Product of Glycolysis Pyruvate stores a significant amount of energy
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The Kreb Cycle (named in 1930 after Hans Kreb) Aka citric acid cycle tricarboxylic acid cycle
Product of Glycolysis • Pyruvate stores a significant amount of energy • If oxygen is present, pyruvate enters the mitochondria where enzymes complete the oxidation (loss of e-) of organic fuel • Processes involved before the Kreb Cycle • Pyruvate’s carboxyl group is removed and given off as a molecule of CO2
The remaining two carbon molecules are oxidized (lose e-) to form acetate • The electrons extracted transfer to NAD+ and store energy in the form of NADH • Side note: NAD + has been reduced here • Coenzyme A (contains sulfur) attaches to the acetyl group, which is very reactive, and produces acetyl coenzyme A (acetyl CoA)
Processes involved during the Kreb Cycle • For each Acetyl CoA that enters the cycle: • Three molecules of NAD+ are reduced to NADH • So six total b/c there are two pyruvates originally that have been convereted into acetyl CoA • Electrons are transferred to FAD (flavin adenosine dinucleotide-derived from vitamin B) • This reduces FAD to FADH2 • Therefore a total of two molecules of FADH2
One molecule of ATP is produced via substrate phosphorylation • Therefore two ATP total • Three molecules of CO2 • Therefore six total (four during the Kreb Cycle and two when pyruvate was converted to acetate) • Reduced enzymes (carrying a lot of chemical energy), NADH and FADH2, move to the last step of cellular respiration, the electron transport chain (ETC)
kreb cycle animation • kreb cycle animation