Link reaction and Krebs cycle Flashcards
Where does the link reaction happen?
Matrix of the mitochondria.
How does pyruvate get into the matrix
Pyruvate is actively transported into the matrix.
How is the pyruvate oxidised?
By the removal of hydrogen which reduces NAD to NADH.
The pyruvate is changed to a 2-carbon molecule called acetate, what molecule does this combine with?
Coenzyme A
How is pyruvate (3 carbons) changed to acetate (2 carbons)?
Pyruvate is decarboxylated (carbon dioxide is removed) which diffuses out of the mitochondria and out of the cell.
What are the 3 products of the link reaction?
Acetyl coenzyme A, reduced NAD and CO2
What does acetyl coenzyme A join with in the Krebs cycle?
A 4-carbon molecule (called oxaloacetate)
What is made when acetyl coenzyme A joins with the 4-carbon molecule?
A 6-carbon (called citrate)
- What is produced in a Krebs cycle?
NADH, FADH, ATP and CO2
Why is it important to produce lots of reduced coenzymes in the Krebs cycle (and also link and glycolysis)?
To provide lots of hydrogen atoms which are split into hydrogen ions and electrons. The electrons are needed for the electron transport chain.
What is decarboxylation
The removal of a carboxyl group to form carbon dioxide
Why is it important to regenerate the 4-Carbon molecule during Krebs?
So that Acetyl from acetyl coenzyme A can be added to produce the 6-Carbon molecule, to start the cycle again, so that no molecules accumulate and become products because there are too many.
Why does the link reaction and Krebs cycle occur in the mitochondria matrix but glycolysis occurs in the cytoplasm?
Glucose is too big to enter the mitochondria so it is split into pyruvate which is small enough to be actively transported into the matrix of the mitochondria.
