Lecture 9 - Introduction to enzymes

Question 1

Enzymes are

Answer 1

biological catalysts

Question 2

Enzymes increase the

Answer 2

rate of a reaction

Question 3

Enzymes speed up reactions, but cannot alter

Answer 3

the equilibrium constant or the free energy change

Question 4

Enzymes lower the

Answer 4

free energy of activation

Question 5

Activation energy is the

Answer 5

energy input required to initiate a reaction

Question 6

The enzyme binds the

Answer 6

substrate

Question 7

The substrate is the

Answer 7

molecule on which an enzyme acts

Question 8

In an enzyme-catalyzed reaction, the substrate is a

Answer 8

reactant

Question 9

In an enzyme-catalyzed reaction, the active site is the

Answer 9

portion of the enzyme surface to which the substrate binds

Question 10

In enzyme-substrate binding, the first step is the

Answer 10

binding of substrate to the enzyme

Question 11

In the lock-and-key model, the substrate binds to

Answer 11

the portion of the enzyme with a complementary shape

Question 12

In the induced fit model, the binding of the substrate

Answer 12

induces a change in the conformation of the enzyme

Question 13

_____ interactions dictate substrate-enzyme binding

Answer 13

non-covalent

Question 14

The binding site is usually a ______ in the enzyme

Answer 14

cleft

Question 15

Enzymes are highly specific in both

Answer 15

binding chiral substrates and catalyzing their reactions

Question 16

The stereospecificity of enzyme binding arises from

Answer 16

the chirality of enzymes (L-amino acids)

Question 17

Transition state analogs are compounds that can be used to

Answer 17

inhibit the activity of an enzyme

Question 18

The functional groups of enzymes are inadequate at catalyzing

Answer 18

oxidation-reduction reactions

Question 19

Enzymes that catalyze oxidation-reduction reactions utilize

Answer 19

cofactors

Question 20

Cofactors can be

Answer 20

metal ions, organic molecules (coenzymes), prosthetic groups

Question 21

Coenzymes are ______ by the enzymatic reaction

Answer 21

chemically changed

Question 22

Coenzymes must be ______ to participate in further enzymatic reactions

Answer 22

returned to their original state

Question 23

Many coenzymes are derived from

Answer 23

vitamins

Question 24

Enzyme activity can be regulated by

Answer 24

1. Control of enzyme availability
2. Control of enzyme activity

Question 25

Substrate binding affinity can be controlled by

Answer 25

small molecules (effectors)

Question 26

Effectors can be

Answer 26

activators and inhibitors

Question 27

ATCase is activated by _____ and inhibited by _____

Answer 27

ATP; CTP

Question 28

CTP and ATP bind to the

Answer 28

regulatory subunits of ATCase

Question 29

Feedback inhibition is a process by which the

Answer 29

final product of a series inhibits the first reaction in the series

Question 30

Activators (ATP) preferentially bind to the

Answer 30

R state

Question 31

Inhibitors (CTP) preferentially bind to the

Answer 31

T state

Question 32

The T to R conformational change brings the two substrates

Answer 32

closer together in the active site