5.7.4(Link reaction and Krebs cycle)

State the name of the process of how ATP is produced

• ATP is generated by substrate level phosphorylation

Describe the role of the link reaction

• It links pyruvate from glycolysis to krebs cycle

Describe the process of the link reaction

• In the matrix of the the mitochondria pyruvate is decarboxylated and dehydrogenated

• This is done by pyruvate dehydrogenase which causes NAD to become reduced NAD by taking hydrogens

• Pyruvate decarboxylase removes a CO2 group from the pyruvate

• This forms an acetyl group

• This combines with Coenzyme A(CoA) to form acetylcoenzyme A

Describe the process of the krebs cycle

• Acetylcoenzyme A combines with oxaloacetate to form citrate

• Citrate is decarboxylased and dehydrogenased to form a 5C compound, one molecule of CO2 and reduced NAD

• the 5C compound is further dehydrogenased and decarboxylased to produce a 4 carbon compound, one CO2 and reduced NAD

• The 4C then undergoes substrate level phosphorylation to produce 1 molecule of ATP

• The 4C is dehydrogenased, producing a different 4C compound and a molecule of reduced FAD

  • Rearrangement of the atoms in the 4 carbon molecule, catalysed by an isomerase enzyme, followed by a further dehyrogenation, regenerate the molecule of Oxaloacetate and a molecule of reduced NAD is produced

List the products made in the krebs cycle

1. 1 ATP molecule is produced per cycle

2. 3 reduced NAD molecules

3. 1 reduced FAd moelcule is produced

Give a brief summer of the krebs cycle

• Enzymes combine the acetylcofactor A with oxaloacetate to form citrate

• Decarboxylation and dehydration occurs

• 1 molecule of ATP is produced

• 3 Molecules of reduced NAD and 1 molecule of reduced FAD is produced during 1 turn