NAD+ reaction

NAD+ reaction

(named in 1930 after Hans Kreb)Aka citric acid cycle tricarboxylic acid cycle

Product of GlycolysisPyruvate stores a significant amount of

energyIf oxygen is present, pyruvate enters the

mitochondria where enzymes complete the oxidation (loss of e-) of organic fuel

Processes involved before the Kreb CyclePyruvate’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 CycleFor 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