Acetyl–CoA Formation and the Krebs Cycle

Aerobic respiration’s second stage: formation of acetyl–CoA and the Krebs cycle. The reactions occur in the mitochondrion’s matrix. Opposite, it takes two cycles of Krebs reactions to break down two pyruvate molecules. After two cycles, all six carbons that entered glycolysis in one glucose molecule have left the cell, in six CO2. Two ATP, eight NADH, and two FADH2 form during the two cycles.Aerobic respiration’s second stage: formation of acetyl–CoA and the Krebs cycle. The reactions occur in the mitochondrion’s matrix. Opposite, it takes two cycles of Krebs reactions to break down two pyruvate molecules. After two cycles, all six carbons that entered glycolysis in one glucose molecule have left the cell, in six CO2. Two ATP, eight NADH, and two FADH2 form during the two cycles.

Acetyl—CoA Formation and the Krebs Cycle pyruvate 0 An enzyme splits a pyruvate coenzyme A AND+ molecule into a two»carbon acetyl group and 002. Coenzyme A - binds the acetyl group (forming . 002 acetyI—CoA). NAD‘r combines with released hydrogen ions 5 and electrons, forming NADH. acety CoA \‘ Sir Hans Adolf Krebs, dis» a The Krebs cycle starts as coverer of the Krebs cycle one carbon atom is transferred from acetyI—CoA to oxaloac» etate. Citrate forms, and coen» coenzyme A ' e The final steps of zyrne A '5 regenerated. citrate oxaloacetate the Krebs cycle regener- ate oxaloacetate. o A carbon atom is removed from an intermediate and leaves the cell as 002. NAD‘r combines with released hydrogen ions and electrons, forming NADH. o NAD+ combines with - hydrogen ions and elec- NAD+ trons, forming NADH. o A carbon atom is removed from another intermediate and leaves the cell as 002, and another NADH forms. e The coenzyme FAD com- bines with hydrogen ions and electrons, forming FADHZ. Pyruvate's three carbon atoms have now exited the cell, in 002. 9 One ATP forms by substrate»|eve| phosphowlation.