Exam 1 | Chp. 2 & 3

Question 1

Apoenzyme

Answer 1

protein core without cofactor

Question 2

cofactor

Answer 2

non-protein that activates complex

Question 3

holoenzyme

Answer 3

apoenzyme + cofactor(s)

Question 4

Enzymes do not alter

Answer 4

chemical bonds

Question 5

Enzymes allow

Answer 5

changes to occur with less energy expended

Question 6

Chemical properties of an active site determine 2 things

Answer 6

• Specificity of an enzyme for its substrate
• The reaction it catalyzes

Question 7

Absolute specificity

Answer 7

enz catalyzes only one rxn

Question 7

Group specificity

Answer 7

enz only acts on molecules w/ specific functional groups

Question 7

Linkage specificity

Answer 7

enz acts on particular types of chemical bonds regardless of mol structure

Question 7

Stereochemical specificity

Answer 7

enz only acts on a particular isomer

Question 8

3 types of cofactors

Answer 8

1. Coenzymes
2. Prosthetic Groups
3. Metal ion activators

Question 9

Coenzyme is a non-protein organic substance that

Answer 9

loosely attached to apoenzyme, related to vitamins

Question 10

Prosthetic Group is a non-protein organic substance that

Answer 10

firmly attached to apoenzyme, ex is NAD, NADP

Question 11

Metal Ion activators

Answer 11

may be an integral part or loosely bound to apoenzyme

Question 12

Oxidoreductases catalyze

Answer 12

redox rxns

Question 13

Transferases catalyze

Answer 13

transfer of functional group

Question 14

Hydrolases catalyze

Answer 14

hydrolysis rxns

Question 15

Lyases catalyze

Answer 15

removal of chemical groups

Question 16

Isomerases catalyze

Answer 16

conversion of bonding patterns

Question 17

Ligases catalyze

Answer 17

coupling of molecules with the hydrolysis of ATP bonds

Question 18

Isoenzymes

Answer 18

different multimeric forms of an enzyme

Question 19

Energy required for a substrate to be activated is provided by

Answer 19

the free energy of binding S to E

Question 20

Enzyme substrate complex breaks down to give these two things

Answer 20

rxn products (P) and free enzyme (E)

Question 21

A rxn can be forced to proceed in only one direction by

Answer 21

using a secondary rxn to remove product from availability

Question 22

Rxn rate is represented by the letter _ and is postive for a ________ _____ and negative for a _______ ___

Answer 22

k; + for forward rxn, - for reverse rxn

Question 23

5 factors that affect enzyme activity

Answer 23

1. substrate concentration 2. enzyme concentration 3. temperature 4. pH 5. cofactors

Question 24

First order kinetics

Answer 24

Velocity and [S] are directly proportional and almost equal. - [S] is rate limiting

Question 25

Forming the E-S complex activates

Answer 25

the substrate molecule

Question 26

Zero order kinetics

Answer 26

Reaction rate is independent of [S]

Question 27

Measuring enzyme activity can only occur if

Answer 27

all reactions are at zero order kinetics

Question 28

The MM constant (Km) is useful for

Answer 28

determining optimal [S] that is not rate limiting

Question 29

If [S] > Km by a factor of 100, the reaction is following

Answer 29

Zero-order kinetics

Question 30

If [S] > Km by a factor of less than 100, the reaction is following

Answer 30

First-order kinetics

Question 31

Km represents the

Answer 31

[S] needed to achieve 1/2 Vmax

Question 32

Activators

Answer 32

Small molecules like Zn++ and Mg++ that increase rxn rate

Question 33

Coenzymes are similar to activators in that

Answer 33

some enzymes require their presence for their full activity

Question 34

Inhibitors

Answer 34

Substances that selectively affect rxn velocity + Km to limit enzyme activity

Question 35

Competitive Inhibitor (Def and Effect on KM + Vmax)

Answer 35

Similar to + competes w/ substrate for active site binding - ↑ Km - No effect on Vmax

Question 36

Noncompetitive Inhibitor (Def and Effect on KM + Vmax)

Answer 36

Binds allosteric (non active) site -> conformational change -> altered active site that doesn't bind substrate - No effect on Km - ↓ Vmax

Question 37

Uncompetitive Inhibitor (Def and Effect on KM + Vmax)

Answer 37

Binds E-S to form ES inhib. complex that yields NO product - ↓ Km - ↓ Vmax

Question 38

You can reverse the action of a competitive inhibitor by

Answer 38

increasing [S]

Question 39

What inhibitor only binds when substrate is bound to enzyme

Answer 39

uncompetitive

Question 40

What inhibitor yields no product

Answer 40

uncompetitive

Question 41

In electrochemistry, the anode is __ and the cathode is __

Question 42

Absorbance and concentration are _____ proportional

Answer 42

directly - As concentration increases so does absorbance