TCA cycle

Question 1

What is the purpose of the TCA cycle?

Answer 1

-generates NADH for the e- transport chain
(Oxidizing acetyl CoA so the electron carriers can be reduced.)
FADH2 is fed directly into the e-transport chian in complex2
-ATP is generated via substrate level phosphorylation
Intermediates formed in the TCA pathway are fed into biosynthetic pathways

Question 2

Which steps are the irreversible, large negative delta G?

Answer 2

citrate synthase

isocitrate dehydrogenase, alpha ketoglutarate dehydrogenase complex

Question 3

Why add the CoA cofactor to acetate?

Answer 3

you want to make a thioester intermediate, a high energy bind, drives the synthesis, oxaloacetate is naturally very low in the cell, and this very negative delta G drives the rxn forward

Question 4

Which steps in the TCA cycle produce CO2?

Answer 4

isocitrate dehydrogenase

alphaketoglutarate DH

Question 5

Which steps in the TCA cycle produce NADH?

Answer 5

isocitrate DH
alpha-ketoglutarate DH
malate DH

Question 6

Which steps in the TCA cycle produce GTP/ATP?

Answer 6

succinyl CoA (succinyl CoA synthetase) succinate

Question 7

How do you switch GTP to ATP?

Answer 7

nucleoside diphosphate kinase

Question 8

Which step makes FADH2?

Answer 8

succinate DH (directly linked to complex 2 of electron transprt chain)

Question 9

How many CO2 from two full turns of the TCA?

Answer 9

4

Question 10

How many NADH from two full turns?

Answer 10

6

Question 11

How many FADH from two full turns?

Answer 11

2

Question 12

How many GTP/ATP from two full turns?

Answer 12

2

Question 13

How many NADH from glycolysis?

Answer 13

2

Question 14

How many ATP from glycolysis?

Answer 14

4

Question 15

How many acetyl-CoA from PDH?

Answer 15

2

Question 16

How many NADH from PDH?

Answer 16

2

Question 17

Which cofactors are involved in the pyruvate dehydrogenase complex reaction? Which enzyme complex is each cofactor located? What is the role of each cofactor?

Answer 17

NADH, FADH2, CoA
NADH - isocitrate DH, alpha KTG DH, malate DH
FADH2 - succinate DH
CoA - citrate synthase, alpha ketoglutarate DH

Question 18

Where is the hydroxyethel transferred to lipoic acid?

Answer 18

interface of E1, E2

Question 19

What really important thing happens at E2?

Answer 19

acetyl group is transferred to CoA, forming Acetyl CoA

Question 20

Which are the regulated, large -delta G steps of TCA?

Answer 20

citrate synthase, isocitrate DH, alpha KTG DH

Question 21

Which step produces GTP? Why is the production of GTP equivalent to the production of ATP?

Answer 21

succinyl CoA synthetase, nucleoside diphosphate kinase