krebs cycle steps

• krebs cycle step 1


  • Acetyl group released from acetyl coenzyme A combines with a 4 carbon compound, oxaloacetate, to form a 6 carbon compound , citrate
• krebs cycle step 2

  • citrate decarboxylated and dehydrogenated, producing a 5C compound, one molecule of carbon dioxide and one molecule of reduced NAD
• krebs cycle step 3


  • This 5C is further decarboxylated and dehydrogenated, producing a 4C compound, one molecule of carbon dioxide and one molecule of reduced NAD
• krebs cycle steps 4


  • This 4C compound combines temporarily with, and is then released from, Coenzyme A. At this stage, substrate-level phosphorylation takes place, producing one molecule ATP.
• krebs cycle steps 5


  • the 4C compound is dehydrogenated, producing a different 4C compound and a molecule of reduced FAD.
• krebs cycle step 6

  • rearrangement of atoms in the 4C molecule, catalysed by an isomerase enzyme, followed by further dehydrogenation, regenerate a molecule of oxaloacetate, so the cycle can continue
• krebs cycle

  
• acetyl CoA reacts with oxaloacetate and forms citrate
• citrate converted back to oxaloacetate
• citrate reforms to oxaloacetate by losing two carbon atoms. carbon atoms lost in the form of CO2 (decarboxylation)
• when citrate turns back into oxaloacetate it loses hydrogen atoms and involves an oxidation reaction (dehydrogenation). hydrogen atoms transfer to NAD which forms NADH
• krebs cycle molecules


  • NADH
  • ATP
  • FADH2
  • CO2
• FAD receives hydrogens and FAD is reduced. turns into FADH2