TOPIC 1: INTRODUCTION

Question 1

All organisms, whether single cells or multicellular need to:

Answer 1

o Obtain energy
o Make proteins
o Regulate the exchange of materials
o Duplicate their hereditary material and reproduce

Question 2

Catabolic pathway

Answer 2

where complex molecules are broken down into simple molecules

Question 3

Anabolic pathway

Answer 3

where simple molecules are used to build larger more complex molecules

Question 4

Activation energy

Answer 4

is the amount of energy required to bring all of the molecules in 1 mole of substrate to the transition state

Question 5

To increase rate of reaction, we either need to:

Answer 5

1. Add more energy to the system
2. Decrease AG‡

Question 6

We use a catalyst to do what

Answer 6

Decrease AG‡

Question 7

Enzymes enhance the reaction rate by

Answer 7

lowering the activation energy - very efficient catalysts

Question 8

Prior to the reaction occuring what is formed?

Answer 8

an enzyme-substrate complex

Question 9

substrate binds to a specific region of the enzyme called the

Answer 9

active site

Question 10

enzyme binding to active site is described as_______ as therefore occurs by relatively _______ chemical bonding such as:

Answer 10

transient

weak

Van der Waal’s forces
Hydrogen bonds
Electrostatic bonds

Question 11

For many enzymes rate of reaction (u) varies with

Answer 11

substrate concentration ([S])

Question 12

The Michaelis-Menten model was first derived in

Answer 12

1913

Question 13

Michaelis-Menten model requires the existence of an _____ as an intermediate

Answer 13

ES complex

Question 14

What is Km value

Answer 14

o Km is the substrate concentration at which the reaction rate is half maximum (Vmax)

Question 15

The smaller the Km, the greater or lesser the affinity the enzyme has for its substrate

Answer 15

greater

Question 16

Enzyme activity is regulated in many ways:

Answer 16

1. Enzyme production
2. Compartmentalization
3. Post-translational modification
4. Environment
5. Activation and inhibition

Question 17

Most enzymes follow what kind of curve

Answer 17

hyperbolic

Question 18

Enzymes can be regulated by

Answer 18

substrate molecules and non-substrate (allosteric) molecules

Question 19

substrate molecules are associated with

Answer 19

homotropic interaction

Question 20

homotropic interaction

Answer 20

• At low [S], when one substrate molecule binds to the enzyme, it makes it easier for the next to bind

Question 21

allosteric enzymes are

Answer 21

oligomeric

Question 22

non-substrate (allosteric) molecules are associated with

Answer 22

heterotropic interaction

Question 23

heterotropic interaction

Answer 23

• Regulation of an enzyme by the binding of an effector molecule at the protein’s allosteric site

Question 24

Positive allosteric effectors (activators)

Answer 24

enhance enzyme activity

Question 25

Negative allosteric effectors (inhibitors)

Answer 25

decrease enzyme activity

Question 26

allosteric regulation is very important in

Answer 26

feedback systems

Question 27

Major parts of the enzyme curve: transition site

Answer 27