Exam 2 M6

Question 1

T/F: biological rxns require catalysts

Answer 1

T

Question 2

what serves as enzymes

Answer 2

proteins and RNA molecules

Question 3

T/F: catalysts are not enzymes

Answer 3

F

Question 4

enzymes catalyze rns under ____ conditions

Answer 4

mild

Question 5

enzymes allow for high degrees of rxn ____

Answer 5

specificty

Question 6

enzymes catalyze 1 or a few ___

Answer 6

closely related rxns

Question 7

T/F: enzymes can’t distinguish btwn stereoisomers

Answer 7

False

Question 8

T/F: enzymes inc rxn rates

Answer 8

T

Question 9

how much do enzymes inc rxn rates

Answer 9

10^6 to 10^12

Question 10

enzymes enable ___

Answer 10

regulation

Question 11

how to regulate enzyme

Answer 11

1)control amount of enzyme in cell via txn (control rate at which RNA is produced that will code for that enzyme) or tsln (control how fast RNA–> protein) mechs

2)control activity of enzyme (different small molecules can act as effector molecules that can speed up an enzyme or slow down an enzyme –> activators vs inhibitors)

Question 12

some enzymes require additional molecules called ____ for their functions

Answer 12

coenzymes

Question 13

Cofactors

Answer 13

1. Cations (ions that stabilize enzyme structure like Zn fingers; can also participate directly in chemical rxns)
2. coenzymes (organic molecules that associate transiently w enzyme; can also participate in chemical rxn and need to be converted back to their initial state for next round of rxn)
3. prosthetic groups (e.g. heme, organic molecules permanently covalently associated w enzyme)

Question 14

active sites are meant to be complementary in ____ to substrate

Answer 14

shape and chemical properties

Question 15

enzymes are HIGHLY

Answer 15

specific

Question 16

enzymes are not ____

Answer 16

rigid

Question 17

enzymes do not alter ____

Answer 17

thermodynamics

Question 18

define transition state

Answer 18

point of highest free energy

Question 19

rate of rxn is directly proportional to

Answer 19

delta G dagger

Question 20

enzymes don’t affect the ____ of equilibrium

Answer 20

position

Question 21

T/F: If a rxn is +deltaG but an enzyme can catalyze it, it will occur

Answer 21

F

Question 22

how do enzymes speed up rxns

Answer 22

by stabilizing TS by reducing deltaG associated w TS, make substrates that resemble TS, or change the pathway to go through a diff TS

Question 23

what causes high delta G

Answer 23

lots of breaking and forming bonds at the same time

Question 24

what is delta delta G dagger

Answer 24

reduction in deltaG dagger by the catalyst; helps determine how much enzyme speeds up rxn

Question 25

enyme does not change overall ___ of a rxn

Answer 25

deltaG

Question 26

enzymes do change ____ of a rxn by lowering delta G associated w TS

Answer 26

kinetics

Question 27

all chem rxns exhibit___

Answer 27

kinetics

Question 28

zero order

Answer 28

rate = k1 A--> B k1 independent of concentration and only depends on rate constant, k1

Question 29

first order

Answer 29

rate = k1[A] A--> B k1 depends on rate constant and also on conc of reactants

Question 30

second order

Answer 30

rate = k1[A][B] A+B --> C k2 depends on rate constant and conc of reactants

Question 31

dissociation constant for ES

Answer 31

Kd = [E][S]/[ES]

Question 32

what does Kd for ES assume

Answer 32

K-1 >> K2

Question 33

which molecules can't you measure in lab

Answer 33

[E], [ES]

Question 34

which molecules can you measure in lab

Answer 34

[P], [E]tot

Question 35

what enzyme did M-M base their model off of

Answer 35

invertase

Question 36

what are the 3 assumptions of M-M's model

Answer 36

1. product does not convert back into substrate (irreversible rxn) 2. rxn is at a steady-state; [ES] remains constant during whole rxn 3. [S] is infinitely large

Question 37

product formation depends on _____ and ___

Answer 37

[ES] and K2

Question 38

M-M equation

Answer 38

v0 = vmax [ S] / (Km + [S])

Question 39

a low [S], line is almost linear but as we inc [S], v inc in a ___ fashion

Answer 39

linear

Question 40

Km = [S] it takes to get to

Answer 40

1/2 Vmax

Question 41

vmax occurs

Answer 41

at high [S] when enzyme is sat vmax = k2 [E]tot

Question 42

Kcat =

Answer 42

Vmax / [E]tot

Question 43

Kcat also known as

Answer 43

turnover number

Question 44

large Kcat =

Answer 44

fast conversion and high turnover #

Question 45

for enzymes that obey M-M kinetics, Kcat =

Answer 45

K2

Question 46

highly efficient enzymes are ___ limited

Answer 46

diffusion

Question 47

overall efficiency of an enzyme depends on both ___ and ____

Answer 47

Kcat and Km

Question 48

Kcat/Km must be less than or equal to

Answer 48

K1

Question 49

efficiency is directly proportional to

Answer 49

Kcat

Question 50

efficiency is indireclty proportional to

Answer 50

Km

Question 51

on LW-B plot: slope =

Answer 51

Km/Vmax

Question 52

on LW-B plot: x-intercept =

Answer 52

-1/Km

Question 53

on LW-B plot: y-intercept =

Answer 53

1/Vmax

Question 54

competitive inhibition blocks the

Answer 54

active site (direclty or allosterically) *block's enzyme's ability to bind substrate*

Question 55

T/F: comp inhibition binds enzymes reversibly or irreversibly

Answer 55

T

Question 56

comp inhibitors often resemble

Answer 56

substrate in structure

Question 57

comp inhibitors best resemble

Answer 57

TS analog

Question 58

product inhibition is an ex of ____ inhibition

Answer 58

competitive

Question 59

inhibitors change the ___

Answer 59

kinetics

Question 60

comp inhibitors bind to

Answer 60

free enzyme

Question 61

KI =

Answer 61

[E][I]/[EI]

Question 62

M-M equation for comp inhibition

Answer 62

V0 = Vmax [ S] / aKm + [S]

Question 63

For comp inhbition, as inc [I], the line shifts to the ___ which means rxn is slower

Answer 63

right

Question 68

alpha depends on

Answer 68

[I] and affinity of E for I

Question 69

Km app =

Answer 69

alpha Km

Question 70

for comp inhibition, alpha only affects

Answer 70

Km

Question 71

slope for comp inhib

Answer 71

alpha Km / Vmax

Question 72

in comp inhib, Vmax

Answer 72

doesnt change

Question 73

if inhibitor binds very tightly, KI ___ and alpha ___

Answer 73

dec; inc

Question 74

uncomp inhibitors bind to

Answer 74

ES complex

Question 75

uncomp inhibitors interfere with

Answer 75

catalysis

Question 76

uncomp inhibitors don't necessarily need to resemble

Answer 76

substrate bc doesn't bind to active site

Question 77

KI' =

Answer 77

[ES][I]/[ESI]

Question 78

uncomp inhib graph looks like

Answer 78

parallel lines

Question 79

why are the parallel lines parallel

Answer 79

bc Vmax and Km are changing proportionally as we inc [I]

Question 80

a' is_____ to [I]

Answer 80

directly proportional

Question 81

a' is _____ to KI

Answer 81

indireclty proprtional

Question 82

uncomp inhibitor effects both ___

Answer 82

Vmax and Km

Question 83

as we add more uncomp inhibitor, Km___and Vmax __

Answer 83

inc; dec

Question 84

new y-int for uncomp inhib

Answer 84

a'/vmax

Question 85

new x-int for uncomp inhib

Answer 85

-a'/Km

Question 86

M-M equation for uncomp inhib

Answer 86

V0 =(vmax/a')[S] / (Km/a') +[S]

Question 87

Km app for uncomp inhib

Answer 87

Km / a'

Question 88

vmax app for uncomp inhib

Answer 88

vmax / a'

Question 89

both vmax and Km is affected by

Answer 89

a'

Question 90

mixed inhib affects both

Answer 90

binding (comp) and catalysis (uncomp)

Question 91

M-M equation for mixed

Answer 91

V0 = (vmax/a')[S] / (aKm/a') + [S]

Question 92

Km app for mixed =

Answer 92

aKm/a'

Question 93

Vmax app for mixed

Answer 93

Vmax/a'

Question 94

in mixed, both a and a' affects

Answer 94

Km