* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download KREBS CYCLE Definition Krebs cycle (aka tricarboxylic acid cycle
Multi-state modeling of biomolecules wikipedia , lookup
Mitochondrion wikipedia , lookup
Lactate dehydrogenase wikipedia , lookup
Size-exclusion chromatography wikipedia , lookup
Basal metabolic rate wikipedia , lookup
Amino acid synthesis wikipedia , lookup
Glyceroneogenesis wikipedia , lookup
Metalloprotein wikipedia , lookup
Electron transport chain wikipedia , lookup
Photosynthesis wikipedia , lookup
Photosynthetic reaction centre wikipedia , lookup
Fatty acid synthesis wikipedia , lookup
Adenosine triphosphate wikipedia , lookup
Fatty acid metabolism wikipedia , lookup
Microbial metabolism wikipedia , lookup
NADH:ubiquinone oxidoreductase (H+-translocating) wikipedia , lookup
Evolution of metal ions in biological systems wikipedia , lookup
Oxidative phosphorylation wikipedia , lookup
Biochemistry wikipedia , lookup
KREBS CYCLE Definition Krebs cycle (aka tricarboxylic acid cycle / citric acid cycle) is the final pathway followed by all carbon atoms derived from carbohydrates, lipids and proteins when they are oxidised during respiration. The main function of the Krebs cycle is to oxidize acetyl-CoA through decarboxylation and dehydrogenation. Acetyl-CoA (2C) H2O CoASH Citrate (6C) Oxaloacetate (4C) Citrate synthase NAD+ NADH + H+ H2O Cis-aconitate (6C) L-Malate (4C0 H2O H2O Fumarase Succinate dehydrogenase Isocitrate dehydrogenase NAD+ NADH + H+ Oxalosuccinate (6C) Succinate (4C0 GDP + Pi GTP Aconitase Isocitrate (6C) Fumarate (4C) FAD FADH2 Aconitase Malate dehydrogenase CoASH Isocitrate dehydrogenase Succinyl-CoA synthetase CoASH CO2 CO2 α-Ketoglutarate (5C) Succinyl-CoA (4C) NAD+ NADH + H+ α-Ketoglutarate dehydrogenase Explanation MAIN STAGES OF EXPLANATION KREBS CYCLE Condensation 1. Acetyl-CoA and oxaloacetate undergo a condensation reaction to form citrate. A coenzyme is released. Isomerization 2. Before the oxidation reactions can begin, the hydroxyl group of citrate must be repositioned. This is done by removing a water molecule from one carbon and the water is added to different carbon. The product is an isomer of citrate called isocitrate. First oxidation 3. Isocitrate is oxidised to form oxalosuccinate. NAD+ is reduced to NADH. 4. Oxalosuccinate is decarboxylated, loses a CO2 and is converted to αketoglutarate. Second oxidation 5. Second oxidative-decarboxylation takes place. α-ketoglutarate is converted to succinyl-CoA. CO2 and NADH are produced. Substrate-level 6. Succinyl-CoA is converted to succinate. The energy released is used for phosphorylation phosphorylation of GDP forming GTP. GTP transfers its phosphate group to ADP forming ATP. Third oxidation 7. Succinate is oxidised to fumarate, two hydrogen atoms are transferred to FAD to form FADH2, Regeneration of oxaloacetate 8. Fumarate becomes hydrated by addition of water is converted to Lmalate. 9. L-malate is oxidised regenerating oxaloacetate, and NAD + is reduced to NADH. Oxaloacetate can be used to combine with acetyl-CoA and the cycle is repeated. Summary 1. 2 molecules of ATP are produced. (From GTP) 2. 6 molecules of reduced NAD are produced. 3. 2 molecules of reduced FAD is produced. 4. 4 molecules of CO2 are produced. 5. 2 oxaloacetate molecules are regenerated, which are used for the Krebs cycle.