Chapter 7

Question 1

enzymes

Answer 1

regulate chemistry of cells and organisms

Question 2

catalysts

Answer 2

enhance rate of reactions

Question 3

active site

Answer 3

region where substrate binds

Question 4

lock and key model

Answer 4

unbound substrate is complementary in shape to the enzyme

Question 5

induced fit

Answer 5

some enzymes assume a complementary shape after the substrate has initially bound

Question 6

cofactor

Answer 6

small non-protein accessory molecule whose presence is required for enzyme activity

Question 7

apoenzyme

Answer 7

without its cofactor

Question 8

holoenzyme

Answer 8

cofactor-bound, active enzyme

Question 9

prosthetic groups

Answer 9

cofactors that binds their enzyme tightly and rarely dissociate

Question 10

Michaelis-Menten

Answer 10

V = Vmax[S] / [S] + Km

Question 11

Turnover number (kcat)

Answer 11

kcat = Vmax / [Et]

Question 12

specificity constant

Answer 12

kcat / Km

Question 13

temperature

Answer 13

as temp increases, rate of reaction increases

Question 14

pH

Answer 14

enzymes function of pH displays a bell-shaped curve

Question 15

enzymatic activators

Answer 15

bind enzymes and increase their activity

Question 16

enzymatic inhibitors

Answer 16

decrease an enzyme’s activity

Question 17

competitive inhibitor

Answer 17

-prevents the substrate from binding the active site of the enzyme
- Vmax stays the same but Km increases

Question 18

uncompetitive inhibitor

Answer 18

-binds only to the enzyme-substrate complex
- Vmax and Km are reduced

Question 19

mixed inhibitor

Answer 19

-bind to an enzyme molecule independently or simultaneously
-Km can increase or decrease while Vmax decreases

Question 20

noncompetitive inhibition

Answer 20

affects Vmax but not Km

Question 21

Lineweaver for inhibition

Answer 21

• competitive (meet on y-axis)
• uncompetitive (parallel)
• mixed (meet off axis)
• noncompetitive (meet on x-axis)

Question 22

irreversible inhibitors

Answer 22

permanently inactivate an enzyme

Question 23

kinetic mechanism

Answer 23

order of binding of substrates and release of products