Rate-determining enzymes (pg 97)

Question 1

Glycolysis

Enzyme/Regulators

Answer 1

Phosphofructokinase-1 (PFK-1)

AMP +, fructose-2,6-bisphosphate +
ATP -, citrate -

Question 2

Gluconeogenesis

Enzyme/Regulators

Answer 2

Fructose-1,6-bisphosphatase

ATP +, acetyl-CoA +
AMP -, fructose-2,6-bisphosphate -

Question 3

TCA cycle

Enzyme/Regulators

Answer 3

Isocitrate dehydrogenase

ADP +
ATP -, NADH -

Question 4

Glycogenesis

Enzyme/Regulators

Answer 4

Glycogen synthase

Glucose-6-phosphate +, insulin +, cortisol +
Epinephrine -, glucagon -

Question 5

Glycogenolysis

Enzyme/Regulators

Answer 5

Glycogen phosphorylase

Epinephrine +, glucagon +, AMP +
Glucose-6-phosphate -, insulin -, ATP-

Question 6

HMP shunt

Enzyme/Regulators

Answer 6

Glucose-6-phosphate dehydrogenase (G6PD)

NADP+ +
NADPH -

Question 7

De novo pyrimidine synthesis

Enzyme/Regulators

Answer 7

Carbamoyl phosphate synthetase II

Question 8

De novo purine synthesis

Enzyme/Regulators

Answer 8

Glutamine-phosphoribosylpyrophosphate (PRPP) amidotransferase

AMP -, inosine monophosphate (IMP) -, GMP -

Question 9

Urea cycle

Enzyme/Regulators

Answer 9

Carbamoyl phosphate synthetase I

N-acetylglutamate +

Question 10

Fatty acid synthesis

Enzyme/Regulators

Answer 10

Acetyl-CoA carboxylase (ACC)

Insulin +, citrate +
Glucagon -, palmitoyl-CoA -

Question 11

Fatty acid oxidation

Enzyme/Regulators

Answer 11

Carnitine acyltransferase I

Malonyl-CoA -

Question 12

Ketogenesis

Enzyme/Regulators

Answer 12

HMG-CoA synthase

Question 13

Cholesterol synthesis

Enzyme/Regulators

Answer 13

HMG-CoA reductase

Insulin +, thyroxine +
Glucagon -, cholesterol -