MCAT Content / Citric Acid Cycle / Net Molecular And Energetic Results Of Respiration Processes

Net molecular and energetic results of respiration processes

Topic: Citric Acid Cycle

The net molecular and energetic results of the glycolysis, the conversion of pyruvate, and the citric acid cycle is 4 ATP, 10 NADH, and 2 FADH2 per molecule of glucose.

The process of glycolysis and conversion of pyruvate to acetyl CoA from one molecule of glucose results in the production of 2 ATP molecules and 4 NADH molecules.

One turn of citric acid cycle produces 1 ATP, 3 NADH, and 1 FADH2 so, a total of 2 ATP, 6 NADH, and 2 FADHare formed per glucose molecule as two citric acid cycles take place for each pyruvate molecule formed from a glucose molecule.

When all these ATP, NADH and FADH2 molecules (i.e. 4 ATP, 10 NADH, and 2 FADH2 per molecule of glucose) enter the oxidative phosphorylation, the net energetic result is 4 + 30 + 4= 38 ATP per glucose as each molecule of NADH produces 3 ATP molecules and each FADH2 produces 2 ATP molecules.

Key Points

• The process of glycolysis, conversion of pyruvate and citric acid cycle produces 4 ATP, 10 NADH, and 2 FADH2 per molecule of glucose.

• The net energetic result is  38 ATP per glucose

Key Terms

citric acid cycle: a series of chemical reactions used by all aerobic organisms to generate energy through the oxidization of acetate derived from carbohydrates, fats, and proteins into carbon dioxide

ATP: a molecule that acts as energy currency in the cells of the body

glycolysis: the first step in the breakdown of glucose to extract energy for cellular metabolism

acetyl-CoA: a molecule that is involved in carbohydrate, lipid, and protein metabolism, and delivers an acetyl group (containing 2 carbons) to the citric acid cycle

pyruvate: any salt or ester of pyruvic acid; the end product of glycolysis

NADH/NAD+: an electron shuttle which delivers high energy electrons to the electron transport chain where they will eventually power the production of 2 to 3 ATP molecules; when this molecule has been oxidized (lost electrons), it is left with a positive charge and is called NAD+

FADH2/FADH: an electron shuttle that carries high energy electrons to the electron transport chain, where they will ultimately drive production of 1 to 2 ATP molecules; the oxidized form is FADH

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