Ch 2: Enzymes

Question 1

Oxidoreductases

Answer 1

catalyze oxidation-reduction reactions that involve the transfer of electrons

Question 2

Transferases

Answer 2

move a functional group from one molecule to another molecule

Question 3

Hydrolases

Answer 3

catalyze cleavage with the addition of water

Question 4

Lyases

Answer 4

catalyze cleavage without the addition of water and without the transfer of electrons

Question 5

Isomerases

Answer 5

catalyze the interconversion of isomers, including both constitutional isomers and stereoisomers

Question 6

Ligases

Answer 6

responsible for joining two large biomolecules, often of the same type

Question 7

Enzymes do NOT alter

Answer 7

free energy (G), enthalpy (H), or final equilibrium position change that accompanies the reaction

Question 8

Enzymes DO alter

Answer 8

rate (kinetics) at which reaction is reached

Question 9

Enzymes bind to the

Answer 9

active site

Question 10

Affect an enzyme’s activity in vitro

Answer 10

temperature, pH, and salinity

Question 11

Reversible inhibition

Answer 11

ability to replace inhibitor with a compound of greater affinity or to remove it using mild laboratory treatment; competitive, noncompetitive, mixed, uncompetitive

Question 12

Competitive inhibition

Answer 12

inhibitor is similar to substrate and binds at the active site and can be overcome by adding more substrate; vmax unchanged, Km increases

Question 13

Noncompetitive inhibition

Answer 13

inhibitor binds with equal affinity to the enzyme and enzyme-substrate complex; vmax decreased Km unchanged

Question 14

Mixed inhibition

Answer 14

inhibitor binds with unequal affinity to the enzyme and the enzyme-substrate complex. vmax decreased, Km unchanged

Question 15

Uncompetitive inhibition

Answer 15

inhibitor binds only with enzyme-substrate complex; Km and vmax both decrease

Question 16

Irreversible inhibition

Answer 16

new enzyme molecules must be made for the reaction to occur again since enzymes altered so active site is unavailable for a prolonged duration

Question 17

Allosteric Sites

Answer 17

occupied by activators which increase either affinity or enzymatic turnover

Question 18

Can alter the activity or selectivity of enzymes

Answer 18

phosphorylation or glycosylation

Question 19

Zymogens

Answer 19

enzymes secreted in inactive form and are activated by cleavage