Link Reaction and Krebs Cycle Flashcards
Link Reaction
- Pyruvic Acid enters the mitochondrion
- Carbon dioxide and hydrogen are removed from the PA by decarboxylase and dehydrogenase enzymes respectively.
- The Pyruvic Acid is combined with coenzyme A (CoA) to form a 2C compound called acetyl CoA.
What is decarboxylation?
When carbon is released as a waste product.
What is dehydrogenation?
When two hydrogen’s are removed and taken up by co enzyme NAD
Krebs Cyle (Only occurs if oxygen is available)
- Acetyl CoA (2C) is combined with oxaloacetate( 4C) to form citrate (6C). Citrate enters the Kreb’s cycle. This involves a series of decarboxylation and dehydrogenation reactions.
- The carbon dioxide is released. The hydrogen which is removed is passed to coenzymes such as NAD and FAD (i.e. the coenzymes are reduced).
- 1 ATP molecules are generated directly in the Kreb’s cycle.
- Eventually the 4C compound (oxaloacetate) is regenerated. This then combines with more
Acetyl CoA and the whole cycle begins again.
Where does the Krebs cycle take place?
Mitochondrial matrix
How many carbon dioxide molecules are produced when each 2-carbon molecule enters the Krebs cycle?
Produces 2 carbon dioxide
How many ATP’s are produced when each 2-carbon molecule enters the Krebs cycle?
1 ATP by substrate-level phosphorylation
How many hydrogen’s are produced when each 2-carbon molecule enters the Krebs cycle?
Four pairs of hydrogen atoms
(2H) x 4
What co-enzyme accepts the 2H atoms produced in the Krebs cycle?
Coenzymes NAD and FAD
What are the phosphorylation reactions that happen in the Krebs cycle?
Phosphorylation is the addition of phosphate
e.g. ADP + Pi=ATP
What are the decarboxylation reactions that happen in the Krebs cycle?
Breaking off of carbon dioxide
e.g. Pyruvate=acetyl CoA + CO2
What are the redox reactions that occur in the Krebs cycle?
Where the substrates are oxidised and reduced.
Oxidised NAD+ elections=reduced NAD
Pyruvate=acetyl CoA + 2H (dehydrogenation)
