Citric Acid Cycle

Question 1

What is the final step of the TCA Cycle?

Via what enzyme?

Answer 1

Maleate —> Oxaloacetate

Via the Malate dehydrogenase enzyme

Question 2

3 catalytic Cofactors of Pyr Dehydrogenase rxn

Answer 2

1. Thiamine Pyrophosphate (TPP)
2. Lipoic Acid
3. FAD

Question 3

1st step of TCA cycle?

Answer 3

1. Condensation of 4C oxaloacetate + Acetyl group = ACoA

2. Oxaloacetate reacts with ACoA and water —> Citrate and CoA

Question 4

What allows all the domains of the PDC complex to work together

Answer 4

The Flexible arm of E2

Question 5

What directly inhibits E2

Answer 5

High [ACoA]

Question 6

Stage 1 of TCA Cycle?

Answer 6

Degradation of Nutrients

Question 7

E2 characteristics

Answer 7

A Trimer that contains 3 distinct domains

Question 8

During LOW energy charge, what ACTIVATES PDH?

Answer 8

1. Pyruvate

2. ADP

Question 9

How is the PDC regulated?

Answer 9

Both allosterically and by phosphorylation

Question 10

Stage 2 of TCA Cycle

Answer 10

Nutrients for an Acetyl CoA pool

Question 11

Stage 3 of TCA cycle

Answer 11

Acetyl CoA entry into TCA

Energy equivalent substances are made (NADH, FADH2, and GTP)

ATP production by way of OxPhos

Question 12

Pyr Dehydrogenase Rnx Req.?

Answer 12

1. 3 enzymes
   E1,E2, and E3
2. 5 Coenzymes
   - 3 Catalytic Cofactors
   - 2 Stoichiometric Cofactors

Question 13

2nd control site for TCA regulation

Answer 13

Isocitrate Dehydrogenase

Question 14

What is the rate limiting step of the TCA Cycle?

What enzyme is used?

Answer 14

Isocitrate —> alpha-ketoglutarate

Via the enzyme Isocitrate Dehydrogenase

Question 15

What is amphibolic rxn?

Answer 15

A rxn that deals with Catabolism and Anabolism

Question 16

What complex is FADH2 associated with?

Answer 16

Complex II

Question 17

What is the only step in the TCA cycle that yields GTP or ATP

Via what enzyme?

SLP or OxPhos

Answer 17

Succinyl CoA —> succinate

Via the enzyme succinyl CoA synthetase

SLP

Question 18

Products created from the TCA Cycle

Answer 18

2 CO2

1GTP

3 NADH
(Both of these high energy e-)
1 FADH2

Question 19

What hormone can stimulate FA synthesis

Answer 19

Insulin

Question 20

During HIGH Energy Charge, what INHIBITS PDH

Answer 20

1. ACoA
2. ATP
3. NADH

Question 21

3 energy sources of nutrients for ACoA

Answer 21

1. Carbs:
   Glucose - Pyr - ACoA
2. Lipids
   TAG - FA - ACoA
3. Proteins
   AA - ACoA

Question 22

Where does the TCA cycle take place?

Answer 22

Inside the Mitochondria

Question 23

1st control site for TCA regulation

Answer 23

Pyruvate Dehydrogenase

Question 24

What step is FADH2 produced in the TCA Cycle?

Via what enzyme?

Answer 24

From Succinate —> Fumarate

Via the Succinate Dehydrogenase

Question 25

Where is Succinate Dehydrogenase located?

Answer 25

In the inner membrane of the Mitochondria

Question 26

2 Stoichiometric Cofactors

Answer 26

1. CoA

2. NAD+

Question 27

What intermediate can be used for the synthesis of AA and Purine Bases

Answer 27

Alpha-ketoglutarate

Question 28

What Links glycolysis to the TCA cycle

Answer 28

Pyruvate dehydrogenase

Question 29

3rd control site for TCA regulation?

Answer 29

Alpha-ketoglutarate Dehydrogenase

Question 30

What enzyme catalyzes the first step of the TCA cycle?

Answer 30

Citrate Synthase

Question 31

Step from Pyruvate to Acetyl CoA

Answer 31

3 total

1. Decarboxylation
2. Oxidation
3. Transfer Acetyl group to CoA

Question 32

Pathway of Pyruvate to TCA

Answer 32

1. Pyr must enter the mitochondria via the Mitochondria Pyr Carrier (MPC)
2. Pyr Dehydrogenase Complex (PDC) catalyzes the decarboxylation of Pyruvate

Question 33

2 major Anaplerotic rxn of the TCA cycle?

Answer 33

1. Degradation of AA

2. Carboxylation of Pyruvate

Question 34

Purpose of the TCA cycle?

Answer 34

Oxidizing Carbon fuels for harvesting HIGH ENERGY E-