Enzymes

Question 1

What is a catalyst?

Answer 1

A catalyst is a substance which can speed up a chemical reaction, without itself being chemically changed at the end of the reaction.

Question 2

What is a enzyme?

Answer 2

Enzymes are proteins that function as biological catalysts. They can speed up chemical reactions. They remain chemically unchanged at the end of the reaction.

Question 3

What is activation energy?

Answer 3

Activation energy is the energy needed to start a chemical reaction.

Question 4

What are the characteristics of enzymes?

Answer 4

1. They speed up chemical reactions.
2. They are required in minute amounts only
3. They are specific in action.

Question 5

How does the ‘lock and key’ hypothesis work?

Answer 5

1. An enzyme has a specific 3D shape which contains an active site.
2. Only the substrate with a 3D shape complementary to that of the active site can fit into the enzyme to form an enzyme-substrate complex
3. Chemical reaction occurs and the substrate is converted into products.
4. Products detach from the active site. Enzymes remain chemically unchanged at the end of the reaction.

Question 6

What is denaturation?

Answer 6

Denaturation is the change of 3D shape of an enzyme or any other soluble protein, caused by heat or chemicals such as acids and alkali.

Question 7

How are enzymes affected by temperature?

Answer 7

1,Enzymes are inactive in low temperatures→Kinetic energy is low

2. Hence, chances of substrate molecules colliding with enzymes are very low.
3. As temperature increases, kinetic energy of molecules increases→increases the chance of collision between substrate and enzyme molecules.→Increases the rate of formation of enzyme substrate complex.
4. The optimum temperature is the point when the rate of reaction is highest and enzyme is most active.
5. Beyond the optimum temperature enzyme activity decreases→high temperatures dentures the enzyme.

Question 8

How are enzymes affected by pH?

Answer 8

1. Different enzymes have different optimum PHs, at which they are most active.
2. Extreme changes in pH denatures the enzyme and cause it to lose function.

Question 9

Why does the rate of reaction increase when temperature increases?

Answer 9

As temperature increases, kinetic energy of both enzyme and substrate molecules increases, thus increasing the chance of collisions between both molecules to form more enzyme substrate molecules per unit time. Thus, the rate of reaction increases when temperature increases.

Question 10

Why is the rate of reaction optimal when the temperature is optimal?

Answer 10

The optimum temperature is where kinetic energy of both enzyme and substrate molecules are the highest causing most number of collisions between them to form enzyme-substrate complexes per unit time, hence the rate of reaction is highest when the temperature is optimum.