Chapter 7

Question 1

Zero order reaction

Answer 1

rate does not depend on concentration of substrate

Question 2

Velocity or rate of reaction is determined by measuring

Answer 2

how much A disappears as a function of time and how much B appears as a functionof time

Question 3

First order concentration

Answer 3

Rate depends on concentration of substrate

Question 4

When the substrate concentration is low, an enzyme
reaction
* a. will display zero-order kinetics.
* b. will display first-order kinetics.
* c. will display second-order kinetics.
* d. will denature and cease to function

Answer 4

b. will display first-order kinetics.

Question 5

initial velocity (V0) for each substrate concentration is determined from the slope of the curve at …

Answer 5

the beginning of a reaction

Question 6

Km is the substrate concentration that yields

Answer 6

1/2 Vmax

Question 7

Low Km indicates

Answer 7

high affinity between enzyme and substrate

Question 8

Michaelis constant KM is related to the

Answer 8

rate constants of individual steps in catalytic scheme

Question 9

Wehn V==1/2 Vmax, the Km =

Answer 9

[S]

Question 10

Hexokinase catalyzes the phosphorylation of glucose and fructose by ATP. Km for glucose is 0.15mmol/L, whereas that for fructose is 1.5mmol/L. Assume V max is the same for both glucose and fructose and the enzyme displays hyperbolic kinetics.

For which substrate does hexokinase have the great affinity?

Also, the comparison of the two sugars for hexokinase indicates which sugar is preferred as a nutrient?

fructose, fructose
glucose, fructose
fructose, glucose
glucose, glucose

Answer 10

glucose, glucose

Question 11

Michaelis Menten equation manipulated into one that yields ________ by equation called

Answer 11

straight line
Lineweaver Burk equation

Question 12

Advantages for lineweaver burkplot

Answer 12

1. Straight line so easier to determine how well points fit in straight line than to a curve
2. effects of inhibitors on reaction can be analyzed more easily

Question 13

KM value is approximately the substrate concentration of the enzyme in _____

Answer 13

vivo

Question 14

k2/kcat

Answer 14

turnover number of enzyme
number of substrate molecules converted into production per second

Question 15

What is the measure of maximum catalytic efficiency?

Answer 15

k2/kcat

Question 16

_____ Kcat/KM indicates more efficient enzyme

Answer 16

higher

Question 17

A –> B -> C –> D –> E –> F
what is the key committed step

Answer 17

A –> B
so B is committed to being converted into F

Question 18

Allosteric enzymes

Answer 18

Quaternary structure
Response to environmental signal
Sigmoidal curve (cooperativity)
Threshold effect
K 0.5

Question 20

Michaelis Menten enzymes

Answer 20

Tertiary structure
Not regulated in the cell
Hyperbolic shape
Km