Rate-Determining Enzymes

Question 1

glycolysis

Answer 1

phosphofructokinase-1 (PFK-1)

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

Question 2

gluconeogenesis

Answer 2

fructose-1,6-bisphosphatase 1

-: AMP, fructose-2,6-bisphosphate

Question 3

TCA cycle

Answer 3

isocitrate dehydrogenase

+: ADP
-: ATP, NADH

Question 4

glycogenesis

Answer 4

glycogen synthase

+: glucose-6-phosphate, insulin, cortisol
-: epinephrine, glucagon

Question 5

glycogenolysis

Answer 5

glycogen phosphorylase

+: epinephrine, glucagon, AMP
-: glucose-6-phosphate, insulin, ATP

Question 6

HMP shunt

Answer 6

glucose-6-phosphate dehydrogenase (G6PD)

+: NADP+
-: NADPH

Question 7

de novo pyrimidine synthesis

Answer 7

carbamoyl phosphate synthetase II

+: ATP, PRPP
-: UTP

Question 8

de novo purine synthesis

Answer 8

glutamine-phosphoribosylpyrophosphate (PRPP) amidotransferase

-: AMP, inosine monophosphate (IMP), GMP

Question 9

urea cycle

Answer 9

carbamoyl phosphate synthetase I

+: N-acetylglutamate

Question 10

fatty acid synthesis

Answer 10

acetyl-CoA carboxylase (ACC)

+: insulin, citrate
-: glucagon, palmitoyl-CoA

Question 11

fatty acid oxidation

Answer 11

carnitine acyltransferase I

-: malonyl-CoA

Question 12

ketogenesis

Answer 12

HMG-CoA synthase

Question 13

cholesterol synthesis

Answer 13

HMG-CoA reductase

+: insulin, thyroxine, estrogen
-: glucagon, cholesterol