Enzymes

Question 1

What is enzyme specificity?

Answer 1

enzymes will only catalyze a single reaction or class or reactions with certain substrates

Question 2

What are oxidoreductases?

Answer 2

catalyze oxidation-reduction reactions; transfer of electrons between biological molecules

Question 3

What is the reductant?

Answer 3

electron donor

Question 4

What is the oxidant?

Answer 4

electron acceptor

Question 5

What are transferases?

Answer 5

catalyze the movement of a functional group from one molecule to another

Question 6

What are kinases?

Answer 6

catalyze the transfer of a phosphate group, generally from ATP, to another molecule

Question 7

What are hydrolases?

Answer 7

catalyze the breaking of a compound into two molecules using the addition of water

Question 8

What are lyases?

Answer 8

catalyze the cleavage of a single molecule into two products

Question 9

What are isomerases?

Answer 9

catalyze the rearrangement of bonds within a molecule

Question 10

What are ligases?

Answer 10

catalyze the addition or synthesis reactions, generally between large similar molecules, and often require ATP

Question 11

What is a substrate?

Answer 11

molecule upon which an enzyme acts

Question 12

What is the enzyme-substrate complex?

Answer 12

physical interaction between enzyme and substrate

Question 13

What is the active site?

Answer 13

location within the enzyme when the substrate is held during the chemical reaction

Question 14

What is the lock and key theory?

Answer 14

suggests that the enzyme’s active site (lock) is already in the appropriate conformation for the substrate (key) to bind

Question 15

What is the induced fit model?

Answer 15

the substrate induces a change in the shape of the enzyme

Question 16

What are cofactors/coenzymes?

Answer 16

nonprotein molecules that are small in size and can bind to the active site of the enzyme and participate in the catalysis of the reaction, usually by carrying charge through ionization, protonation, or deprotonation

Question 17

What are apoenzymes?

Answer 17

enzymes without cofactors

Question 18

What are holoenzymes?

Answer 18

enzymes with cofactors

Question 19

What are prosthetic groups?

Answer 19

cofactors or coenzymes that are necessary for enzyme function

Question 20

Ideal pH for most enzymes in the body

Answer 20

7.4

Question 21

Ideal pH for gastric enzymes in the body

Answer 21

2

Question 22

Ideal pH for pancreatic enzymes in the body

Answer 22

8.5

Question 23

What is feedback regulation?

Answer 23

enzymes are subject to regulation by products further down a give metabolic pathway

Question 24

What is feedforward regulation?

Answer 24

enzymes may be regulated by intermediates that precede the enzyme in the pathway

Question 25

Zymogens

Answer 25

contain a catalytic (active) domain and regulatory domain

Question 26

What is competitive inhibition?

Answer 26

when the inhibitor binds at the active site of the enzyme

Question 27

What is noncompetitive inhibition?

Answer 27

bind to an allosteric site instead of the active site, which induces a conformational change

Question 28

What is mixed inhibition?

Answer 28

results when an inhibitor can bind to either the enzyme or the enzyme-substrate complex, but has different affinity for each

Question 29

What is uncompetitive inhibition?

Answer 29

only bind to the enzyme-substrate complex

Question 30

What is the effect of competitive inhibition on Km and Vmax?

Answer 30

Km - increases

vmax = unchanged

Question 31

What is the effect of noncompetitive inhibition on Km and Vmax?

Answer 31

Km = unchanged
Vmax = decreases

Question 32

What is the effect of mixed inhibition on Km and Vmax?

Answer 32

Km = increases or decreases
Vmax = decreases

Question 33

What is the effect of uncompetitive inhibition on Km and Vmax?

Answer 33

Km = decreases
Vmax = decreases