Oxidation of Pyruvate and TCA Cycle Flashcards Preview

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Flashcards in Oxidation of Pyruvate and TCA Cycle Deck (24):
1

Oxidation of pyruvate and the TCA cycle account for complete oxidation of glucose to what?

CO2 and H2O

2

Pyruvate formed in the cytosol is transported into the mitochondrion by a ____ ____

proton symporter

3

Inside the mitochondrion, pyruvate is oxidatively decarboxylated to acetyl-CoA by ____ ____ multienzyme complex

pyruvate dehydrogenase (PDH)

note: 3 enzymes, 5 coenzymes, regulatory proteins

4

Pyruvate is covalently bound to ___ associated with first enzyme of the pyruvate dehydrogenase

TPP

5

Dihydrolipoyl transacetylase catalyzes the transfer of acetyl group to CoA-SH, which leaves the lipoic acid in the ____, ____ form

reduced; sulfhydryl

6

The oxidized form of _____ is regenerated by dihydrolipoyl dehydrogenase

lipoamide

7

Activity of the PDH complex is affected by _____/_____

phosphorylation/dephosphorylation

note: inactive when phosphorylated

8

Where does the TCA cycle take place in the cell?

matrix of mitochondria

9

In regards to the TCA cycle, oxidation of acetylCoA produces reduced ____ and ____

NADH; FADH2

10

In regards to the TCA cycle, deoxidation of NADH and FADH2 through the ____ ____ chain, reduces O2 to H2O

electron transport

11

What are other roles of citrate?

source of other synthetic pathways (FAs)
regulation of other reactions (PFK-1)
source of reducing equivalents

12

The isomerization of citrate to isocetrate by aconitase is ___, with the migration of the -OH from the central carbon of citrate being always adjacent to the carbon which is derived from the -CH2- of OAA

sterospecific

13

Which enzyme produces the first NADH and CO2 of the TCA cycle

Isocitrate DH

14

What is the rate limiting step of the TCA cycle?

isocitrate to alpha-ketoglutarate

enzyme: isocitrate DH

15

alpha-ketoglutarate dehydrogenase has 3 catalytic subunits E1, E2, and E3. Give the requirements of this enzyme, and mention if it is regulated by phosphorylation.

requires: TPP, lipoid acid, CoASH, FAD, NAD+
NOT regulated by phosphorylation

16

Which enzyme produces the second NADH and CO2 of the TCA cycle?

alpha-ketoglutarate DH

17

What is the only substrate level phosphorylation of the TCA cycle?

Succinyl CoA synthetase/succinate thiokinase

18

Which enzyme of the TCA cycle produces FADH2 (third reducing equivalent

succinate DH

19

Which enzyme of the TCA cycle produces the fourth (and final) reducing equivalent, NADH?

malate DH

20

What determines the rate of the TCA cycle?

rate of ATP utilization

21

Citrate synthase is inhibited by ____-___

succinyl-CoA

22

Isocitrate DH is stimulated by ____, inhibited by ____

ADP; ATP

23

alpha-ketoglutarate is inhibited by _____-___, ___ and ____

succinyl-CoA; NADH; GTP

24

What is the grand total of aerobic oxidation of one mole of glucose (total ATP)?

38