1.4.5 The link reaction and Krebs cycle
- Created by: JTY3
- Created on: 20-04-16 14:12
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- The link reaction
- Pyruvate dehydrogenase removes hydrogen atoms from pyruvate.
- Pyruvate decarboxylase removes a carboxyl group, which eventually becomes CO2, from pyruvate.
- The coenzyme NAD accepts the hydrogen atoms
- Coenzyme A (CoA) accepts acetate, to become acetyl coenzyme A. CoA carrys acetate to the krebs cycle
- 2 pyruvate + 2NAD + 2CoA > 2CO2 + 2 reducedNAD +2 acetyle CoA
- No ATP is produced
- The Krebs cycle
- The Krebs cycle takes place in the mitochondrial matrix .
- It is series of enzyme-catalysed reactions that oxidise the acetyl group of acetyl CoA to 2 molecules of CO2.
- It also produces 1 ATP by substrate level phosphorylation
- Reduces 3 NAD
- potential to produce more ATP in oxidative phosphorylation
- Reduces 1 FAD
- potential to produce more ATP in oxidative phosphorylation
- Reduces 1 FAD
- Reduces 3 NAD
- It also produces 1 ATP by substrate level phosphorylation
- It is series of enzyme-catalysed reactions that oxidise the acetyl group of acetyl CoA to 2 molecules of CO2.
- 1. Acetate is offloaded from coenzyme A and joins with a 4C compound called oxaloacetate to form citrate 6C
- 2. Citrate is decarboxylated and dehydrogenated to form a 5C compound.
- The 2 H are accepted by 1 NAD which becomes reduced.
- 3. The 5C compound is decarboxylated and dehydrogenated to form a 4C compound
- Another reduced NAD is formed.
- 4. 4C is changed into another 4C during which an ADP is phosphorylated to form ATP
- 5. The second 4C is changed into another 4C.
- 2 H atoms are accepted by FAD to make reduced FAD.
- 6. The third 4C is further dehydrogenated and regenerates oxaloacetate
- Another NAD is reduced.
- 5. The second 4C is changed into another 4C.
- 2. Citrate is decarboxylated and dehydrogenated to form a 5C compound.
- Products of the Krebs cycle.
- 6 reduced NAD
- 2 reduced FAD
- 4 CO2
- 2 ATP
- Although oxygen isn't used in these stages of respiration, they wont occur in its absence.
- The link reaction
- Pyruvate dehydrogenase removes hydrogen atoms from pyruvate.
- Pyruvate decarboxylase removes a carboxyl group, which eventually becomes CO2, from pyruvate.
- The coenzyme NAD accepts the hydrogen atoms
- Coenzyme A (CoA) accepts acetate, to become acetyl coenzyme A. CoA carrys acetate to the krebs cycle
- 2 pyruvate + 2NAD + 2CoA > 2CO2 + 2 reducedNAD +2 acetyle CoA
- No ATP is produced
- The link reaction
- The Krebs cycle takes place in the mitochondrial matrix .
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