explain krebs cycle biology
Krebs Cycle, also called the Citric Acid Cycle, is a pathway in cellular respiration that converts acetyl-CoA, a two-carbon molecule derived from carbohydrates, proteins, and fats, into NADH and FADH2, two electron carriers that drive the synthesis of ATP through oxidative phosphorylation. The process takes place in the mitochondrial matrix of eukaryotic cells and the cytoplasm of prokaryotic cells.
The Krebs Cycle consists of eight enzymatic reactions that take place in a cyclical manner, with each reaction catalyzed by a specific enzyme. The cycle starts with the condensation of acetyl-CoA and oxaloacetate to form citrate, which is then converted to isocitrate by the enzyme aconitase. Isocitrate is then oxidized to alpha-ketoglutarate by isocitrate dehydrogenase, producing NADH in the process. Alpha-ketoglutarate is then converted to succinyl-CoA by alpha-ketoglutarate dehydrogenase, generating another molecule of NADH.
Succinyl-CoA is then converted to succinate by the enzyme succinyl-CoA synthetase, producing a molecule of GTP (which is used to synthesize ATP). Succinate is then oxidized to fumarate by succinate dehydrogenase, which is a part of the mitochondrial electron transport chain and generates FADH2 during the process. Fumarate is then converted to malate by the enzyme fumarase, which is then converted back to oxaloacetate by malate dehydrogenase, producing another molecule of NADH in the process.
The completion of the Krebs Cycle leads to the production of 3 NADH, 1 FADH2, 1 GTP (or ATP), and 2 carbon dioxide molecules. The NADH and FADH2, along with the electron carrier ubiquinone, feed into the electron transport chain, which generates a proton gradient across the mitochondrial inner membrane. The energy stored in this gradient is used to drive the synthesis of ATP through the process of oxidative phosphorylation.
Overall, the Krebs Cycle plays a crucial role in energy production in living cells by breaking down acetyl-CoA and generating electron carriers that can be used to generate ATP.