Lecture 28 - TCA Cycle

Question 1

The f(X) portion of Acetyl-CoA is the ______.
A. Adenine molecule
B. Phosphate portion
C. Sulfated carbonyl group

Answer 1

C. Sulfated carbonyl

Question 2

ATP production occurs in the _______ of the mitochondria.

Answer 2

Matrix

Question 3

Electrons are transferred between compounds via what molecules?
A. CO2 and H2O
B. CO2 and FAD
C. NADH and FADH2

Answer 3

C. NADH and FADH2

Question 4

The production of _____ from _____ is the only producer of nucleotide Triphosphates in the TCA cycle.

Answer 4

Succinate from succinylCoA

Question 5

In oxidative phosphorylation, electrons are used to reduce \_\_\_\_\_. 
A. NAD+
B. O2
C. FADH
D. CO2

Answer 5

B. O2

Question 6

The high energy elections formed by the TCA cycle produces _____ in the intermembrane space via the electron transport chain.

Answer 6

H+ gradient

Question 7

Compartmentalization of the Kreb's cycle occurs by moving pyruvate into. 
A. Cytosol
B. Mitochondria
C. Nucleus
D. Golgi

Answer 7

B. Mitochondria

Question 8

Pyruvate dehydrogenase is important in the ___________ of pyruvate. It it requires __________ as a prosthetic group.

Answer 8

oxidative decarboxylation of pyruvate; TPP

Question 9

The dihydrolipoyl portion of pyruvate dehydrogenase is important in the ___________. It it requires __________ as a prosthetic group.

Answer 9

transfer of acetyl group to CoA; Lipoamide

Question 10

Dihydrolipoyl dehydrogenase is important in the ___________. It it requires __________ as a prosthetic group.

Answer 10

regeneration of oxidized lipoamide; FAD

Question 11

Catalytic co-factors are prosthetic groups for formation of acetyl-CoA by pyruvate dehydrogenase. What are the catalytic cofactors?

Answer 11

TPP; lipoic acid; FAD

Question 12

Pyruvate dehydrogenase requires cofactors that function as substrate. What are they?

Answer 12

CoA and NAD

Question 13

What is a “stoichiometric cofactor?

Answer 13

A cofactor that acts as a substrate

Question 14

Production of acetyl-CoA occurs where?
A. Intermembrane space
B. Mitochondrial matrix
C. On the outer mitochondrial membrane
D. On the inner mitochondrial membrane

Answer 14

B. Mitochondrial matrix

Question 15

Production of Acetyl-CoA from pyruvate occurs in three steps. What are they?

Answer 15

1) Decarboxylation of pyruvate to form CO2
2) Oxidation of acetyl group
3) Transfer of acetyl group to CoA

Question 16

lipoamide is found on what domain of the PDH complex?
A. E1
B. E2
C. E3

Answer 16

B. E2

Question 17

Regeneration of the lipoamide molecule requires the addition of what cofactor?

Answer 17

FAD, which becomes FADH2

Question 18

FAD is produced after the regeneration of lipoamide. What are the other products of this reaction?

Answer 18

NADH and H+ (high e- electrons that go into the ETC)

Question 19

Draw the PDH complex. Include the stochiometric cofactors, catalytic cofactors, and the reactions.

Answer 19

Place the picture here.

Question 20

The reoxidation of the lipoamide chain occurs in what PDH subunit?
A. E1
B. E2
C. E3
D. All of the above

Answer 20

E3

Question 21

Which stoichiometric cofactor "visits" each subunit?
A. NAD+
B. FAD
C. Lipoamide
D. TPP

Answer 21

C. Lipoamide

Question 22

_____ activates pyruvate dehydrogenase phosphatases. This results in increased PDH activity.

Answer 22

ADP and pyruvate; ADP indicates a low energy charge and pyruvate is a PDH substrate

Question 23

______ acts to activate pyruvate dehydrogenase kinase, which decreases PDH activity

Answer 23

Acetyl-CoA; acetyl-CoA is an end product of PDH

Question 24

Isocitrate dehydrogenase is important to the production of isocitrate from citrate. Why is this important in the TCA cycle? What enzyme is used?

Answer 24

Citrate is NOT able to undergo the decarboxylation to alpha-KG. Isocitrate, however, is.

Aconitase is the enzyme

Question 25

(-) regulation of IDH

Answer 25

ATP; NADH (end products of TCA)

Question 26

(+) regulation of IDH

Answer 26

ADP (indicates low E*, and requires “jump-starting” TCA cycle)

Question 27

What steps produces NADH/CO2?

Answer 27

Isocitrate->alpha-ketogluterate;

alpha-ketogluterate-> succinyl-CoA

Question 28

What steps produce NADH only?

Answer 28

Malate to oxaloacetate

Question 29

What steps produce GTP?

Answer 29

Succinyl-CoA —> Succinate

Question 30

What step produces FADH2?

Answer 30

Succinate —> Fumarate

Question 31

Like PDH, alpha-ketoglutarate dehydrogenase joins the product of the reaction to ____.

Answer 31

CoA

Question 32

The final four steps of the TCA cycle are responsible for ___.

Answer 32

Regeneration of oxaloacetate

Question 33

Oxaloacetate regeneration converts a methylene in fumarate to ________ in oxaloacetate.

Answer 33

carbonyl

Question 34

High energy electrons are released from enzymes in all steps of the TCA cycle except:

A. Succinyl CoA to Succinate with ATP generation
B. Succinate to Fumarate with FADH2 production
C. Malate to Oxaloacetate with NADH production
D. Isocitrate to alpha-ketoglutarate with NADH production

Answer 34

A.

Question 35

Malate oxidation to oxaloacetate has a + deltaG. How is this overcome?

Answer 35

• By the movement of NADH into the ETC

- By the use of oxaloacetate to form citrate (by citrate synthase)