Enzymology

Question 1

Turnover rate of an enzyme refers to

Answer 1

The fastest speed of an enzym

Question 2

Enzymes work by reducing

Answer 2

Gibbs free energy of activation

Question 3

Endergonic reactions are_________ and have a ________ G value

Answer 3

Non-spontaneous; positive

Question 4

Exergonic reactions are__________ and have a _______G value

Answer 4

Spontaneous; negative

Question 5

Enzymes do not change the overall Gibbs free energy change for the reaction OR the equilibrium concentrations of substrates and products. T/F

Answer 5

True

Question 6

Hydrolysis of ATP is often used to drive other chemical reactions. T/F

Answer 6

True

Question 7

What are the functions of proteases

Answer 7

To break down proteins

Question 8

What is the function of the hexokinase enzyme

Answer 8

To transfer a phosphoryl group

Question 9

The enzyme chymotrypsin is found where? What is its function

Answer 9

Small intestines

Digestive enzyme

Question 10

The active site of chymotrypsin includes what amino acids?

Answer 10

Serine, histidine, and aspartic acid

Question 11

Cofactors are proteins. T/F

Answer 11

False

Question 12

Cofactors are of two types. What are they?

Answer 12

Coenzymes

Metal ions

Question 13

Cofactors participate in catalysis by

Answer 13

Providing functional groups

Question 14

In humans, cofactors are usually synthesized by

Answer 14

Vitamins

Question 15

What reactions do oxide-reductases catalyze ?

Answer 15

Oxidation and reduction reactions

Question 16

An example of an oxidoreductase is

Answer 16

Alcohol dehydrogenase

Question 17

A common cofactor of alcohol dehydrogenase is

Answer 17

NAD+

Question 18

What kind of reaction does transferases catalyze

Answer 18

Transfer of C-, N-, or P- containing groups

Question 19

An example of a transferase is_______ and its function is_______

Answer 19

Glycerol kinase

To Transfer a phosphate group to glycerol to prepare it for glucose conversion during gluconeogenesis in the liver

Question 20

What reactions do hydrolases catalyze?

Answer 20

Catalyze cleavage bonds by adding water

Question 21

examples of a hydrolases include

Answer 21

Proteases, esterases, lipases,

Question 22

What reactions do lyases catalyze ?

Answer 22

Catalyze cleavage of C-C, C-S, and some C-N bonds

Question 23

What reactions do isomerases catalyze ?

Answer 23

Catalyze rearrangements of of isomers

Question 24

What reactions do ligases catalyze

Answer 24

Formation of carbon and; O, S and N bonds

Essentially binding of 2 molecules

Question 25

Competitive inhibitors bind to

Answer 25

The active site

Question 26

Non-competitive inhibitors bind to

Answer 26

Anywhere other than the active site

Question 27

Un-competitive inhibitors bind to

Answer 27

Anywhere other than the active site ONLY when the substrate is bound to the enzyme

Question 28

What happens to Vmax and Km during competitive inhibition

Answer 28

Vmax remains the same, Km increases.

Question 29

Small Km reflects _______ affinity of enzyme for the substrate

Answer 29

High

Question 30

Large Km reflects________ affinity of the enzyme for the substrate

Answer 30

Low

Question 31

For Lineweaver-Burk plots, the line representing competitive inhibition_________ on the y-axis with the uninhibited reaction

Answer 31

Intersect

Question 32

What happens to Km and Vmax in no competitive inhibition

Answer 32

Km stays the same, Vmax decreases

Question 33

What happens to Km and Vmax in uncompetitive inhibition

Answer 33

Both decrease

Question 34

Suicide inhibition is when the inhibitor_________bonds to the enzyme and ________the concentration of the enzyme

Answer 34

Covalently; reduces

Question 35

What happens to Km and Vmax in suicide inhibition

Answer 35

Vmax is decreased, Km stays the same

Question 36

An example of suicide inhibition is

Answer 36

Penicillin

Question 37

all enzymes follow Michaelis menten kinetics. T/F

Answer 37

False, allosteric enzymes do not

Question 38

How many substrate binding sites do allosteric inhibitors have

Answer 38

At least 2

Question 39

Allosteric activators ________ the Km and cause the enzyme to bind to substrate more readily

Answer 39

Decrease

Question 40

Allosteric Inhibitors ________ the Km and cause the enzyme to bind less readily to substrate

Answer 40

Increase

Question 41

Allosteric activators can only bind to the enzyme when the enzyme is in _____ configuration and inhibitors can only bind the enzym during_____ configuration

Answer 41

R; T