Link reaction and Krebs cycle

  • Created by: Hindleyc
  • Created on: 04-11-18 19:54
First step of link reaction
Pyruvate is actively transported across the mitochondrial membrane into the matrix (small enough to get through)
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Step 2
Pyruvate is oxidised and decarboxylated to Acetate.
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What happens in this process
pyruvate loses a carbon dioxide molecule and 2 hydrogen molecules
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What are hydrogens accepted by?
NAD to from reduced NAD
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step 3?
2 carbon Acetate molecule now combines with coenzyme A to form a molecule called Acetyl coenzyme A
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Overall steps?
Pyruvate- Acetate by losing CO2 and 2H that combines with 2NAD to form 2NADH. Acetate+ coenzyme A= Acetyl coenzyme A
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Notes?
This happens twice after glycolysis because 2 pyruvate molecules are produced therefore Krebs cycle happens twice too.
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Where Krebs cycle?
Matrix of mitochondria
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What does cycle involve?
Series of redox reactions to produce a single molecule of ATP (per acetyl coenzyme A) (substrate level phosphorylation) reduced FAD and reduced NAD
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What is there also a series of?
Decarboxylation reactions resulting in the release of carbon dioxide.
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Step 1
4c oxaloacetic acid combines with 2c Acetyl coenzyme A producing citric acid 6c and coenzyme A.
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Step 2
Citric acid is decarboxylated twice losing 2 carbons (CO2)
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Step 3
Reduced FAD, NAD and 2NAD so citric acid oxidised -redox rxn removing Hydrogen and reducing coenzymes
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step 4
Substrate level phosphorylation- phosphate from substrate combines with ADP forming ATP
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How is this different to oxidative phosphorylation?
Phosphate derived from chemicals in cycle
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step 5
Substrate (citric acid) regenerated to oxaloacetic acid
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Products?
Reduced coenzymes FAD and NAD. ATP molecule, 2 molecules of CO2
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Summary
2 decarboxylations, 4 oxidations of citric acid, 1 molecule through substrate level phosphorylation
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diagram
Oxaloacetic acid- Citric acid by 2c acetyl coA- CoA so add 2 c. Citric acid- oxaloacetic acid by losing 2 co2, NAD, 2NAD, FAD,ATP
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Card 2

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Step 2

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Pyruvate is oxidised and decarboxylated to Acetate.

Card 3

Front

What happens in this process

Back

Preview of the front of card 3

Card 4

Front

What are hydrogens accepted by?

Back

Preview of the front of card 4

Card 5

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step 3?

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Preview of the front of card 5
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