How many redox reactions are in the citric acid cycle

You are subscribed. Subscribe Now. Trial Session Enrollment. The Next Class:. Enter Session. Enroll in course. Welcome Back! Please sign in to continue. Sign in with Facebook. Sign in with Google. Sign in with email. No account, yet? Sign Up. Please sign up to continue. Sign up with Facebook. Sign up with Google. Sign up with email. Already signed up? Sign In Here. We had trouble validating your card. It's possible your card provider is preventing us from charging the card.

Please contact your card provider or customer support. Cardholder's Name. Security Code. It is 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.

Each stage in the cycle and in the link reaction — pyruvate conversion into acetyl CoA occurs twice for every glucose molecule that enters glycolysis because 2 pyruvate molecules are produced for each glucose. Therefore The eight steps of the citric acid cycle are a series of redox, dehydration, hydration, and decarboxylation reactions. Removal of electrons from a molecule is called as oxidation.

This subsequently lowers the energy content of a molecule. Most biological oxidations involve the loss of hydrogen atoms. This type of oxidation is referred to as a dehydrogenation and enzymes used for this purpose are called as dehydrogenases. It involves the gain of oxygen atoms. It is the opposite of oxidation. It is the addition of electrons to a molecule when a molecule is oxidized, the liberated hydride ions H- do not remain free in the cell.

In order to harness the energy of these electrons, they are immediately transferred to another compound by coenzymes. It is characterized by the loss of oxygen atoms. Therefore thus. An enzyme called pyruvate dehydrogenase complex splits each molecule of pyruvate into a molecule of CO 2 and a two-carbon acetyl group.

The CO 2 diffuses out of the cell, and the acetyl group combines with a molecule called coenzyme A abbreviated as CoA.

The product of this reaction is acetyl-CoA. Acetyl CoA, which carries the two-carbon degradation product of glycolysis enters the cycle by combining with the oxaloacetate to give S -citryl CoA. The addition is catalyzed by the citrate synthase. This transformation yields the molecule isocitrate. Two events occur in reaction 3 of the citric acid cycle. In reaction 4 of the citric acid cycle, alpha-ketoglutarate loses a carbon dioxide molecule and coenzyme A is added in its place.

The enzyme that catalyzes this reaction is alpha-ketoglutarate dehydrogenase. The mechanism of this conversion is very similar to what occurs in the first few steps of pyruvate metabolism. The resulting molecule is called succinyl-CoA. The enzyme succinyl-CoA synthetase catalyzes the fifth reaction of the citric acid cycle.

In this step a molecule of guanosine triphosphate GTP is synthesized. GTP is a molecule that is very similar in its structure and energetic properties to ATP and can be used in cells in much the same way.