Chapter 8 : Enzyme Kinetics

Question 1

Enzymes

Answer 1

A substance produced by a living organism that acts as a catalyst that brings about a specific biochemical reaction

Question 2

Why are enzymes so imporant ?

Answer 2

Enzymes control the speed of biochemical reactions to keep the body functioning

Question 3

The specificity of an enzyme is determined by

Answer 3

It’s active site

Question 4

How is an enzyme named ?

Answer 4

By adding -ase to the end

Question 5

What are the six classes of enzymes?

Answer 5

• oxidoreductases
• transferases
• hydrolases
• lyases
• isomerases
• ligases

Question 6

Oxioreductases

Answer 6

Enzymes used for oxidation reduction reactions

Question 7

Transferases

Answer 7

Enzymes used for transfer of functional groups

Question 8

Hydrolases

Answer 8

Enzymes used for hydrolysis reactions

Question 9

Lyases

Answer 9

Enzymes used for addition of double bonds

Question 10

Isomerases

Answer 10

Enzymes used for isomerization reactions

Question 11

Ligases

Answer 11

Enzymes used for the formation of bonds with ATP cleavage

Question 12

What are cofactors

Answer 12

A non-protein chemical compound of metallic ion that is required for a protein’s biological activity to happen. They can be considered helper molecules

Question 13

What is a coenzyme ?

Answer 13

Non-protein molecules that participate in catalysis when bonded to the active site of the enzymeTr

Question 14

True or false, coenzymes are often vitamins or contain vitamins as part of their structure

Answer 14

True

Question 15

Prosthetic group

Answer 15

When a coenzyme is covalently bonded to the enzyme

Question 16

Holoenzyme

Answer 16

Contains the catalytically active complex of the protein and the prosthetic group

Question 17

Apoenzyme

Answer 17

A protein with the catalytically inactive complex but without the prosthetic group

Question 18

Specificity

Answer 18

Enzyme acts only on a specific substrate; lock and key theory

Question 19

Induced fit model

Answer 19

The shape of an enzyme’s active site is modified when binding to the substrate -> change in conformation

Question 20

For a reaction to take place spontaneously, ΔG must be

Answer 20

negative

Question 21

If a catalyst is present in a reaction , does ΔG change ?

Answer 21

No , ΔG stays the same and depends only on the energy of the reactants and products and respective concentrations.

Question 22

What can ΔG tell us about the rate of the reaction

Answer 22

ΔG indicates nothing about the rate, only if it will occur spontaneously or not

Question 23

Free Energy Change Equation

Answer 23

ΔG = ΔG’ +RTln [C][D]/ [A][B]

Question 24

What does ΔG’ represent ?

Answer 24

the standard free energy change ( the concentration of reactants and products are at constant pressure : 1 atm and constant pH: 7

Question 25

What does R represent ?

Answer 25

Gas constant

Question 26

Without catalysts , are reactions favorable ?

Answer 26

No they are usually unfavorable in the environment and tend to be very slow. A catalyst is needed to increase the rate of a reaction

Question 27

True or False, a chemical reaction will occur if reactions do not have the energy to achieve the transition state

Answer 27

False, reactions will occur if reactants have the energy needed to achieve transition state to undergo rearrangement

Question 28

The rate of any chemical reaction is proportional to the concentration of the _______ molecules having the ______ state energy

Answer 28

reactant , transition

Question 29

The higher the _______-_ energy, the less likely that molecules will have this energy and the slower the reaction will occur

Answer 29

transition state

Question 30

Activation energy ( Ea)

Answer 30

Energy required to raise the average energy of the reactants to transition state energy

Question 31

What is one way to lower the activation energy

Answer 31

Increase temperature