Lecture 22 TCA

Question 0

where does the TCA cycle occur and where is ATP produced?

Answer 0

occurs in mitochondrial matrix, in the mitochondrial cristae in the inner membrane

Question 1

What are the 3 characteristics of the TCA cycle?

Answer 1

aerobic conditions
more ATP generated than glycolysis
occurs in mitochondria

Question 2

pyruvate to acetyl CoA requires how many enzymes and how many coenymes?

What are they?

Answer 2

3, 5

TPP, Lipoic acid, FAD
CoA, NAD (stoichiometric cofactors)

Question 3

What are the 3 steps to generate acetyl CoA from pyruvate?

Answer 3

1) Decarboxylation
2) Oxidation
3) Transfer acetyl group to CoA

Question 4

Carboxylation reaction

Answer 4

CO2 lost to create hydroxylethyl-TPP, catalyzed by E1

decarboxylation occurs BEFORE protonation in the mechanism

Question 5

Oxidation Reaction

Answer 5

hydroxyethyl oxidized to acetyl and transferred to lipoamide creating a rich thioester bond

Question 6

Formation of acetyl group

Answer 6

acetyl group transferred to CoA
E2 catalyzed
thioester bond remains

Question 7

PDH regeneration

Answer 7

transfer electrons to return lipoamide to orginal form
2 electrons transferred to FAD, then to NAD+
oxidized lipoamide catalyzed by E3

Question 8

What links glycolysis to the TCA?

Answer 8

PDH via acetyl CoA creation

Question 9

PDH regulation

Answer 9

regulated allosterically and by reverse phosphorylation

high acetyl CoA inhibits E2