Chapter 19 (Citric Acid Cycle Regulation)

Question 1

Fatty acid synthesis requires ___ in the cytosol

Answer 1

Acetyl-CoA

Question 2

Cytosolic acetyl-CoA is generated from the breakdown of ___

Answer 2

Citrate

Question 3

Amino acid biosynthesis uses ___ and ___ as starting materials

Answer 3

alpha-ketoglutarate

oxaloacetate

Question 4

Anaplerotic reaction know as ___ reactions

Answer 4

filling up

Question 5

The ___ is essentially a source of free energy for aerobic organisms

Answer 5

Citric acid cycle

Question 6

Pyruvate Decarboxylase

Answer 6

Anaplerotic
Converts Pyruvate into OAA by adding a CO2 onto the last C
Requires: ATP + CO2
Produces: ADP + Pi
Irrevesible

Question 7

Malic Enzyme

Answer 7

Anaplerotic 
Converts Pyruvate into L-Malate by adding a CO2 onto the last C and hydrolizing the keto group
Requires: NADPH + H + CO2
Produces: NADP+
Reversible

Question 8

3 Irreversible reactions of the TCA Cycle

Answer 8

Citrate Synthase
Isocitrate Synthase
Alpha-ketoglutarate Dehydrogenase

Question 9

Pyruvate Dehydrogenase is regulated via product inhibition by ___ and ___

Answer 9

High concentration of NADH and Acetyl-CoA
Drive the reversible reactions of E2 and E3 backwards
TPP is trapped on the E1 in the hydroxyethyl form (because of the CO2)

Question 10

PDH is covalently modified by phos/dephos of ___

Answer 10

E1

Question 11

___ and ___ activate the enzyme ___ that phosphorylates ___ and inactivates it

Answer 11

NADH and Acetyl-CoA
pyruvate dehydrogenase kinase
E1

Question 12

___ activates pyruvate dehydrogenase by activating ___

Answer 12

Ca 2+

pyruvate dehydrogenase synthase

Question 13

Calcium simulates ___ and the production of ___

Answer 13

muscle contractions

ATP

Question 14

Pyruvate Dehydrogenase regulation
Activates:
Inhibits:

Answer 14

Activates: NAD+ and CoA
Deactivates: Acetyl-CoA, NADH and ATP

Question 15

The 3 irreversible steps of the TCA cycle are all deactivated by high concentrations of ___

Answer 15

NADH

Question 16

When we slow down the TCA cycle we get a build up of ___ (which allosterically regulates ___)

Answer 16

citrate

PFK

Question 17

Increased concentrations of ATP inhibits the enzymes ___ and ___

Answer 17

Citrate Synthase

Isocitrate Dehydrogenase

Question 18

The three most important regulators of the TCA cycle are

Answer 18

Acetyl-CoA
OAA
NADH

Question 19

An increase in Acetyl-Coa will pull the Malate Dehydrogenase reaction toward

Answer 19

OAA

Question 20

The concentration of malate v. OAA depends fluctuates with

Answer 20

NADH/NAD concentrations
NADH + OAA
NAD + malate

Question 21

The Glyoxylate Pathway is important for ___ and allows the bypass of ___ and gives us a net production of ___

Answer 21

growing seeds
CO2 producing steps
OAA
(mammals do not have this pathway)