Saturday, January 28, 2023
Mitochondrial Health

Kreb,s Cycle, TCA Cycle, Citric Acid cycle with easy diagram and steps and mnemonic😊😊

What is the Krebs Cycle? Also known as the citric acid cycle, the Krebs cycle or TCA cycle is a chain of reactions occurring in the mitochondria, through which almost all living cells produce energy in aerobic respiration. It uses oxygen and gives out water and carbon dioxide as products.
The Krebs Cycle releases energy from Acetyl–CoA, but the cellular challenge is to release the energy gradually and in useable forms.

Steps in the Krebs Cycle

Step 1: Citrate synthase. …

Step 2: Aconitase. …

Step 3: Isocitrate dehydrogenase. …

Step 4: α-Ketoglutarate dehydrogenase. …

Step 5: Succinyl-CoA synthetase.

Oxidative Decarboxylation of pyruvate to Acetyl CoA.

Step 1: Condensation of acetyl CoA with oxaloacetate.

Step 2: Isomerization of citrate into isocitrate.

Step 3: Oxidative decarboxylations of isocitrate.

Step 4: Oxidative decarboxylation of α-ketoglutarate.

Pyruvate—three carbons—is converted to acetyl CoA, a two-carbon molecule attached to coenzyme A. A molecule of coenzyme A is a necessary reactant for this reaction, which releases a molecule of carbon dioxide and reduces a NAD+ to NADH.

aerobic conditions, pyruvate enters the citric acid cycle and undergoes oxidative phosphorylation leading to the net production of 32 ATP molecules. In anaerobic conditions, pyruvate converts to lactate through anaerobic glycolysis. Anaerobic respiration results in the production of 2 ATP molecules.
Lactate dehydrogenase. The major cytosolic fate of pyruvate produced by PK is reduction to lactate. LDH is a ubiquitously expressed enzyme that reversibly catalyzes reduction of pyruvate to L-lactate coupled with the oxidation of NADH to NAD+.

Why is oxygen needed for pyruvate?

In the presence of oxygen, pyruvate is transformed into an acetyl group attached to a carrier molecule of coenzyme A. The resulting acetyl CoA can enter several pathways, but most often, the acetyl group is delivered to the citric acid cycle for further catabolism.

Why is ATP 36 instead of 38?

Explanation for Correct option: The citric acid cycle produces 36 ATP molecules. So, in aerobic respiration, a total of 38 molecules of ATP are created, with 2 ATP molecules formed outside the mitochondria.

What are two functions of glycolysis?

Glycolysis is a cytoplasmic pathway which breaks down glucose into two three-carbon compounds and generates energy. Glucose is trapped by phosphorylation, with the help of the enzyme hexokinase.

Where most of the ATP is produced?

mitochondrial matrix

The majority of ATP synthesis occurs in cellular respiration within the mitochondrial matrix: generating approximately thirty-two ATP molecules per molecule of glucose that is oxidized.


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