Biochemistry - Metabolism

Question 1

enzyme terminology: kinase

Answer 1

*an enzyme that catalyzes transfer of a phosphate group from a high-energy molecule (usually ATP) to a substrate

Question 2

enzyme terminology: phosphorylase

Answer 2

*adds inorganic phosphate onto substrate without using ATP

Question 3

enzyme terminology: phosphatase

Answer 3

*removes phosphate group from substrate

Question 4

enzyme terminology: dehydrogenase

Answer 4

*catalyzes oxidation-reduction reactions

Question 5

enzyme terminology: hydroxylase

Answer 5

*adds hydroxyl group (-OH) onto substrate

Question 6

enzyme terminology: carboxylase

Answer 6

*transfers carboxyl groups (-COOH) with the help of biotin

Question 7

enzyme terminology: mutase

Answer 7

*relocates a functional group within a molecule

Question 8

enzyme terminology: synthase

Answer 8

*catalyzes synthesis reactions without using ATP as a source of energy

Question 9

rate-determining enzyme of: glycolysis

Answer 9

*phosphofructokinase-1

*positive regulators = AMP, fructose-2,6-bisphosphate
*negative regulators = ATP, citrate

Question 10

rate-determining enzyme of: gluconeogenesis

Answer 10

*fructose-1,6-bisphosphate

*negative regulators = AMP, fructose-2,6-bisphosphate

Question 11

rate-determining enzyme of: TCA cycle

Answer 11

*isocitrate dehydrogenase

*positive regulators = ADP
*negative regulators = ATP, NADH

Question 12

rate-determining enzyme of: glycogenesis

Answer 12

*glycogen synthase

*positive regulators = glucose-6-phosphate, insulin, cortisol
*negative regulators = epinephrine, glucagon

Question 13

rate-determining enzyme of: glyogenolysis

Answer 13

*glycogen phosphorylase

*positive regulators = epinephrine, glucagon, AMP
*negative regulators = glucose-6-phosphate, insulin, ATP

Question 14

rate-determining enzyme of: HMP shunt

Answer 14

*glucose-6-phosphate dehydrogenase

*positive regulators = NADP+
*negative regulators = NADPH

Question 15

rate-determining enzyme of: de novo pyrimidine synthesis

Answer 15

*carbamoyl phosphate synthetase II

*positive regulators = ATP, PRPP
*negative regulators = UTP

Question 16

rate-determining enzyme of: de novo purine synthesis

Answer 16

*glutamine-phosphotibosylpyrophosphate (PRPP) aminotransferase

*negative regulators = AMP, IMP, GMP

Question 17

rate-determining enzyme of: urea cycle

Answer 17

*carbamoyl phosphate synthetase I

*positive regulator = N-acetylglutamate

Question 18

rate-determining enzyme of: fatty acid synthesis

Answer 18

*acetyl-CoA carboxylase (ACC)

*positive regulators = insulin, citrate
*negative regulators = glucagon, palmitoyl-CoA

Question 19

rate-determining enzyme of: fatty acid oxidation

Answer 19

*carnitine acyltransferase I

*negative regulator = malonyl-CoA

Question 20

rate-determining enzyme of: ketogenesis

Answer 20

*HMG-CoA synthase

Question 21

rate-determining enzyme of: cholesterol synthesis

Answer 21

*HMG-CoA reductase

*positive regulators = insulin thyroxine, estrogen
*negative regulators = glucagon, cholesterol

note - this is the enzyme that is inhibited by statins

Question 22

metabolic processes that occur in the mitochondria

Answer 22

*fatty acid oxidation (beta oxidation)
*acetyl-CoA production
*TCA cycle
*oxidative phosphorylation
*ketogenesis

Question 23

metabolic processes that occur in the cytoplasm

Answer 23

*glycolysis
*HMP shunt
*cholesterol synthesis (smooth ER)
*protein synthesis (rough ER)
*fatty acid synthesis
*nucleotide synthesis

Question 24

metabolic processes that occur in both the cytoplasm & mitochondria

Answer 24

*heme synthesis
*urea cycle
*gluconeogenesis