TCA Cycle

Question 1

What is the overall output of the TCA cycle?

Answer 1

1 Glucose + 6O2 _6 CO2 + 6H2O + 38 ATP

Question 2

What transforms pyruvate into Acetyl-CoA?

Answer 2

Pyruvate dehydrogenase complex

Question 3

What are the parts of pyruvate dehydrogenase complex?

Answer 3

3 enzymes, 5 vitamin B derived cofactors

Question 4

How is pyruvate dehydrogenase different from _-ketoglutarate dehydrogenase?

Answer 4

PDHC CAN be deactivated via phosphorylation

Question 5

Citrate synthase

Answer 5

Acetyl-CoaA + Oxaloacetate _ Citrate + CoASH. Irreversible rxn. 1st source of reducing equivilents

Question 6

Aconitase

Answer 6

Citrate _ Isocitrate

Question 7

Isocitrate dehydrogenase

Answer 7

Isocitrate _ _-ketoglutarate. Rate limiting step of TCA cycle**. Produces NADH and CO2

Question 8

_-ketoglutarate dehydrogenase

Answer 8

_-ketogluarate _Succinyl-CoA. Irreversible rxn. Similar structure to PDHC. CANNOT be regulated via phosphorylation. Produces NADH and CO2

Question 9

Succinyl CoA synthetase/ Succinyl thiokinase

Answer 9

Succinyl-CoA _ Succinate. Only substrate level phosphroylation if the TCA cycle*

Question 10

Nucleotide diphosphokinase

Answer 10

Phosphorates ATP from GTP (after succinyl thiokinase step)

Question 11

Succinate dehydrogenase

Answer 11

Succinate _Fumarate. Produces FADH2

Question 12

Fumarase

Answer 12

Fumarate _ Malate. Uses H2O

Question 13

Malate dehydrogenase

Answer 13

Malate _ Oxaloacetate (NADH)

Question 14

Malate -Aspartate Shuttle

Answer 14

Replensishes NAD+ in cytosol and NADH in inner mitochondria membrane for electron transport chain

Question 15

What inhibits citrate synthase?

Answer 15

SuccinylCoA

Question 16

What inhibits Isocitrate DH?

Answer 16

ATP

Question 17

What stimulates Isocitrate DH?

Answer 17

ADP

Question 18

What inhibits _-KGDH?

Answer 18

succinyl-CoA, NADH, GTP