Chapter 7- Enzymes (1)

Question 1

What is entropy?

Answer 1

A measure of the amount of energy which is unavailable to do work.

Question 2

How do chemical reactions effect entropy?

Answer 2

It increases entropy

Question 3

Entropy favours a reaction to increase what?

Answer 3

Disorder. The higher the entropy, the greater the disorder.

Question 4

What is activation energy?

Answer 4

The initial energy needed to start a chemical reaction.

Question 5

What often supplies the activation energy?

Answer 5

Thermal energy from cells

Question 6

What do enzymes do to the activation energy of a reaction?

Answer 6

It decreases the activation energy of a reaction.

Question 7

What is the definition of enzymes?

Answer 7

Enzymes are biological catalysts that speed up chemical reactions.

Question 8

What does the active site do?

Answer 8

The active site has a specific binding site which binds to a specific substrate molecule.

Question 9

Enzymes are a type of what?

Answer 9

Protein

Question 10

How do enzymes increase the rate of production?

Answer 10

By reducing the activation energy

Question 11

Enzymes catalyse a reaction by…

Answer 11

Stabilising the transition state.

Question 12

What is the transition state?

Answer 12

Transition state is the highest activation energy on a reaction coordinate in which the molecule is partially reacted.

Question 13

An enzyme is complementary to what in order for the reaction to take place?

Answer 13

The transition state. NOT THE SUBSTRATE.

Question 14

What are the enzyme models?

Answer 14

1- Lock and key model

2- Induced fit model

Question 15

Describe the lock and key model

Answer 15

• The shape of the enzyme active site and substrate fit together perfectly.
• The two shapes are considered rigid and fixed

Question 16

Describe the induced fit model

Answer 16

• Binding of the substrate slightly changes the structure of the active site of the enzyme.
• The enzyme may also slightly distort the substrate.

Question 17

What is enzyme kinetics?

Answer 17

How reaction velocity rates change with varying substrate concentration

Question 18

In order to find out how velocity changes, what would you measure?

Answer 18

You would measure the rates of enzyme- catalysed reactions at different substrate and enzyme concentrations.

Question 19

What is the reaction equilibrium?

Answer 19

Amount of product formed increases with time, until a time is reached where there is no net change in the concentration. This is the reaction equilibrium.

Question 20

What is the Michaelis constant (Km)

Answer 20

Tells you the substrate concentration, at which half the enzyme is bound to the substrate.

Question 21

What does the Michaelis constant (Km) indicate?

Answer 21

Indicates how well a substrate binds with a given enzyme.

Question 22

What does a small Km indicate?

Answer 22

A small Km indicates that the enzyme only requires a small amount of substrate to become saturated.

Question 23

What does a large Km indicate?

Answer 23

A large Km indicates the need for high substrate concentrations to become saturated.

Question 24

What is Km important for?

Answer 24

If you want to try and inhibit enzymes in the body.

A large number of therapeutic drugs are enzyme inhibitors.