It refers to a complex series of chemical reactions that produce carbon dioxide and Adenosine triphosphate (ATP), a compound rich in energy. The cycle occurs by essentially linking two carbon coenzyme with carbon compounds; the created compound then goes through a series of changes that produce energy. This cycle occurs in all cells that utilize oxygen as part of their respiration process.
It occurs in the matrix of the mitochondria in the presence of CO2.Pyruvic acid diffuses from cytoplasm to the matrix of the mitochondria.Pyruvic acid is oxidized and broken down into energy,CO2 and H2O as shown;
CH3COCOOH + O2 CO2 + H2O + Energy
Diagram showing the Krebs Cycle
Other names of Krebs Cycle;
Citric Acid Cycle
Tricarboxylic Acid Cycle
Stages in which C02, H2O and Energy is released;
1: Glycolysis ("splitting of sugar"): This step happens in the cytoplasm.
One Glucose (C6H12O6) is broken down to 2 molecules of pyruvic acid. Results in the production of 2 ATPs for every glucose
2: Transition Reaction: Pyruvic Acid is shuttled into the mitochondria, where it is converyed to a molecule called Acetyl CoA for further breakdown.
3: The Krebs Cycle, or Citric Acid Cycle: Occurs in the mitochondrial matrix, the liquid part of the mitochondria.
4: The Electron Transport Chain and Chemiosmosis ("the big ATP payoff"). Occurs in the christae of the mirochondria, the folded membranes inside the chloroplast.
How many Enzymes are involved in the Krebs Cycle?
There are 8 enzymes involved in the cycle.These are;
1. Citrate
2. Isocitrate
3. Alpha-ketoglutarate
4. Succinul-CoA
5. Succinate
6. Malate
7. Fumarate
8. Oxaloacetate
How many Stages does the cycle have?
a)Formation of acetyl CoA
The raw material for citric acid cycle is acetyl CoA. It is formed from fatty acids by b-oxidation and from pyruvic CoA to form Acetyl Co A. This reaction is catalysed by a set of enzymes called pyruvic acid dehydrogenase.