Chapter 4- Enzymes

Question 1

What is an enzyme?

Answer 1

An enzyme is a protein that function as biological catalysts. They can speed up or alter reactions while remaining unchanged at the end of the reaction.

Question 2

What are the functions of enzymes?

Answer 2

1. Digestion of food molecules.
2. Break down of molecules during respiration.
3. Build and synthesize complex substances.
4. Break down poisonous substances.

Question 3

Describe the lock and key hypothesis.

Answer 3

1. Only one kind of enzyme can act on a specific substrate, due to the 3D shape of the enzyme that makes it specialized. (Complementary)
2. The substrate can bind to the active site of the enzyme, forming an enzyme-substrate complex.
3. Chemical reaction occurs while substrate is bound to the active site.
4. Product leaves the active site, enzyme remains unchanged.

Question 4

Describe the induced fit hypothesis.

Answer 4

1. The shape of the active site may not be exactly complementary to the substrate.
2. Enzyme changes its shape to fit the substrate.
3. It is still able to form an enzyme-substrate complex.

Question 5

State how temperature affects an enzyme.

Answer 5

1. Optimum temperature: 40-45 degrees.
2. For every 10 degrees, the rate doubles.
3. Temperature affects kinetic energy and collisions.
4. Once it is past the optimum temperature, the enzyme starts to denature as the temperature breaks the bonds that keep the enzyme protein in shape. No longer able to function.

Question 6

State how pH affects an enzyme.

Answer 6

1. Optimum pH depends on the type of enzymes.

2. Enzymes denature as they lose their shapes in extreme pHs.

Question 7

What are the five key characteristics of enzymes?

Answer 7

1. It lowers activation energy and provides and alternative path.
2. It is required in minute amounts.
3. It catalyses reversible reactions.
4. It is specific in action.
5. It can denature.