Enzymes

Question 1

A common biological reaction without enzyme catalysis will take

Answer 1

750,000,000 years

Question 2

Enzymes are

Answer 2

biological catalysts that accelerate the rate of a reaction

Question 3

Most enzymes are …….

A few enzymes are …….. that are made up of ……….

Answer 3

proteins
ribozymes
RNA

Question 4

Enzymes are not ……….. ………… during the reaction

Answer 4

permanently changed

Question 5

Properties of enzymes

Answer 5

• highly efficient
• highly specific
• regulation

Question 6

Ratio of catalyzed reaction to uncatalyzed reactions

Answer 6

kcat/kuncat

for some reactions, this can be up to 10^17

Question 7

Classes of enzyme specificty

Answer 7

absolute
group
linkage
stereochemical

Question 8

Absolute

Answer 8

enzyme reacts with only one substrate

Question 9

Group

Answer 9

enzyme catalyzes reaction involving any molecules with same functional group

Question 10

Linkage

Answer 10

enzyme catalyzes the formation or break up of only certain category or type of bond

Question 11

stereochemical

Answer 11

enzyme recognizes only 1 of 2 enantiomers

Question 12

How do catalysts work?

Answer 12

increase the rate of reactions by lowering the activation energy

Question 13

Activation Energy

Answer 13

the energy required to break bonds

Question 14

Every enzyme has an

Answer 14

active site

Question 15

Active site

Answer 15

pocket or groove on enzyme that binds to substrate

Question 16

Substrate

Answer 16

the reactant on which an enzyme works

Question 17

Mechanism of enzyme action

Answer 17

enzyme binds w/ substrate
product is formed at a lower activation energy
product is released

Question 18

Induced fit enzyme model

Answer 18

assumes that the enzyme active site is more a flexible pocket whose conformation changes to fit the substrate molecule

Question 19

Lock and key

Answer 19

the enzyme is assumed to be the lock and the substrate the key
-the enzyme and substrate are made to fit exactly

Question 20

Why is the lock and key model outdated?

Answer 20

the model fails to take into account protein’s conformational changes to fit a substrate molecule

Question 21

Chemical composition of enzymes

Answer 21

can either be simple or complex enzymes (holoenzymes)

Question 22

Complex enzymes don’t function without the

Answer 22

non-protein part

Question 23

Non-protein part can be

Answer 23

• cofactor
• coenzyme
• prosthetic group

Question 24

Inorganic cofactor- minerals

Answer 24

• inorganic

- small

Question 25

Conenzyme-vitamins

Answer 25

• organic

- larger

Question 26

NAD contains the vitamin

FAD contains the vitamin

Answer 26

B3 and B2

Question 27

Both cofactors and coenzymes are not covalently bound to

Answer 27

the enzyme

Question 28

Prosthetic group

Answer 28

tightly bound to the enzyme

Question 29

Enzyme for urea

Answer 29

urease

Question 30

Nomenclature of Enzymes

Answer 30

• in most enzymes names end in -ase
• others are named for the substrate and the reaction catalyzed
• some are historical-no direct relationship to substrate or reaction type

Question 31

Enzymes are often classified according to the reactions they carry out

Answer 31

oxidoreductase
transferase
hydrolase
lyase
isomerase
ligase

Question 32

Oxidoreductase

Answer 32

catalyzes redox reaction

-reductases and oxidases

Question 33

Transferase

Answer 33

transfer a group from 1 molecule to another

• transaminases catalyze transfer of an amino group
• kinases transfer a phosphate group

Question 34

Hydrolase

Answer 34

break bonds by adding water
phosphatases
peptidases
lipases

Question 35

Lyases

Answer 35

catalyze removal of molecules to form double bonds or the reverse to break double bonds

• decarboxylases
• synthases

Question 36

Isomerases

Answer 36

catalyze intramolecular rearrangements

• epimerases
• mutases

Question 37

Ligases

Answer 37

catalyze the joining energy