Lecture 21 & 25 - Nuc & Glyc Regulation

Question 1

What compound negatively regulates adenylosuccinate reductase?

Answer 1

AMP

Question 2

What regulates IMP dehydrogenase?

Answer 2

(-) GMP

Question 3

PRPP synthetase is regulated by what compounds?

Answer 3

(+) Pi

-) GMP, IMP, AMP (purine nucleotides

Question 4

A deficiency in nucleotide reductase would result in:
A. Greater [RNA]
B. Lesser [RNA]
C. Greater [DNA]

Answer 4

A. Greater [RNA]

Question 5

Fumerate is an intermediate of _____ & may funnel into ____.

Answer 5

Purine synthesis; TCA Cycle

Question 6

Production of carbamoyl-phosphate is regulated how?

Answer 6

(+) PRPP

(-) UTP

Question 7

PRPP —> _______ via enzyme ________ is the committed step of purine synthesis.

Answer 7

Phosphribosylamine; glutamine phosphoribosyl pyrophosphate amidotransferase

Question 8

Irreversible reactions of glycolysis:
A. Hexokinase, phosphfructokinase, pyruvate kinase
B. Hexokinase, phosphofructokinase, G-3-P dehydrogenase
C. Hexokinase, enolase, pyrivate kinase

Answer 8

A. Hexokinase, phosphofructokinase, pyruvate kinase

Question 9

Which stage of glycolysis is known as the “committed step?
A. Stage 3
B. Stage 2
C. Stage 1

Answer 9

C. Stage 1

Question 10

(-) regulator of hexokinase

Answer 10

Glucose-6-P (product of reaction)

Question 11

(-) regulator of liver glucokinase

Answer 11

Glucagon, F-6-P (fructose can enter into glycolysis in the liver)

Question 12

(+) regulator of glucokinase

Answer 12

Glucose, fructose 1-P (substrate of glucokinase in the liver), insulin

Question 13

(-) regulator of phosphofructokinase

Answer 13

ATP

Citrate

Question 14

(+) regulator of phosphofructokinase

Answer 14

AMP

Fructose-2,6-BP (downstream product of this enyzme’s product)

Question 15

What does elevated [citrate] indicate to phosphofrucokinase?

Answer 15

A presence of many carbon skeletons available for use

Question 16

High [BGL] produces a dephosphorylation of \_\_\_\_\_, which increases pyruvate/ATP production.
A. Enolase
B. Phosphofructokinase
C. Pyruvate kinase
D. Triose phosphate isomerase

Answer 16

C. Pyruvate kinase

Question 17

Describe the changes to the dual-domain enzyme phosphofructokinase.

Answer 17

The PFK portion is a kinase. When blood glucose is high, ADP is phosphorylated to form ATP. This increases release of glucose from glycogen.

The FBPase is a phosphatase. With decreased blood glucose levels, ATP is dephosphorylated. This phosphorylation of ADP comes from the removal of the Pi from FBPase. This dephosphorylation produces greater gluconeogenesis.