enzymes

Question 1

enzymes

Answer 1

most are proteins. all are catalysts. not used up in reactions. highly specific. accelerate reactions

Question 2

what are the 6 enzyme classes?

Answer 2

oxidoreductases, transferases, hydrolases, lyases, isomerases, and ligases

Question 3

oxidoreductases

Answer 3

oxidation-reduction reactions

Question 4

transferases

Answer 4

group transfer reactions

Question 5

hydrolases

Answer 5

hydrolysis reactions

Question 6

lyases

Answer 6

addition or removal of groups to form double bonds

Question 7

isomerases

Answer 7

isomerization ( intramolecular group transfer)

Question 8

ligases

Answer 8

ligation of two substrates at the expense of ATP hydrolysis

Question 9

holoenzyme

Answer 9

the active enzyme with its non-protein component

Question 10

apoenzyme

Answer 10

the enzyme without its non-protein moiety and is inactive

Question 11

cofactor

Answer 11

non-protein moiety that is a metal ion (minerals)

Question 12

coenzyme

Answer 12

small organic molecules (vitamins)

Question 13

what do enzymes alter?

Answer 13

reaction speed

Question 14

lock and key model

Answer 14

enzyme’s tertiary structure consists of a unique pocket or site which is tailor made to fit only its substrate

Question 15

induced fit model

Answer 15

as enzymes interact with substrates they change their conformation so that the enzyme is snug around the substrate

Question 16

factors affecting reaction rates

Answer 16

temperature, pH, enzyme concentration, and substrate concentration

Question 17

Vo

Answer 17

initial velocity of reaction

Question 18

[S]

Answer 18

concentration of substrate

Question 19

Vmax

Answer 19

the theoretical maximal rate of the reaction

Question 20

Km

Answer 20

substrate at which the reaction velocity is equal to 1/2 Vmax

Question 21

inhibitor

Answer 21

any substance that can diminish the velocity of an enzyme-catalyzed reaction

Question 22

irreversible inhibitors

Answer 22

bind to enzymes through covalent bonds

Question 23

reversible inhibitors

Answer 23

bind to enzymes through noncovalent bonds

Question 24

competitive inhibition

Answer 24

inhibitor binds reversibly to the same site as substrate

Question 25

noncompetitive inhibition

Answer 25

inhibitor binds to different sites than enzymes

Question 26

allosteric enzymes

Answer 26

have multiple subunits. can either inhibit or increase enzyme activity

Question 27

homotropic effectors

Answer 27

substrate serves as effector, enhancing other substrate-binding sites. binding to one site “helps” other sites

Question 28

heterotropic effectors

Answer 28

effector different from substrate, effector may be the product, + feeds back to cause inhibition

Question 29

homotropic positive

Answer 29

substrate that is the same as the initial chemical activates itself

Question 30

heterotropic positive

Answer 30

substrate that is different from the initial molecule is activating the reaction

Question 31

homotropic negative

Answer 31

substrate that is the same as initial molecule in reaction is inhibiting reaction mechanism

Question 32

heterotropic negative

Answer 32

substrate that is different from initial reaction molecule inhibits the reaction

Question 33

Michaelis-Menten non-competitive

Answer 33

covalent, irreversible. decreases Vmax

Question 34

Michaelis-Menten competitive

Answer 34

non-covalent, reversible. increases substrate and Km