Chapter 4: Enzymes

Question 1

Definition and Function of Enzymes

Answer 1

Enzymes are protein catalysts that increase the rate of chemical reactions without being used up in the response itself.
They are precise and only bind to and act on certain molecules called substrates.

Question 2

Structure and Active Site of Enzymes

Answer 2

Enzymes have a specific three-dimensional structure with a defined active site.
The active site is a region on the enzyme that has a complementary shape to the substrate, allowing for specific binding.

Question 3

The Enzyme-Substrate Complex

Answer 3

The substrate binds to the active site of the enzyme, forming an enzyme-substrate complex.
This binding can induce a slight change in the shape of the enzyme (induced fit) to optimize the reaction.

Question 4

How Enzymes Work

Answer 4

Enzymes lower the activation energy required for a reaction to occur, making it happen faster.

They can achieve this by:
Bringing the reacting molecules (substrates) closer together.
Weakening bonds in the substrates.
Orienting the substrates in a specific way to facilitate the reaction.

Question 5

Factors Affecting Enzyme Activity

Answer 5

Temperature, pH, Substrate concentration, Enzyme concentration and Inhibitors.

Question 6

Temperature

Answer 6

Increased temperature generally increases enzyme activity up to an optimal point. Beyond that, enzymes can become denatured (lose their shape and function) at high temperatures.

Question 7

pH

Answer 7

Enzymes have an optimal pH range for activity. Deviations from this range can affect the shape and activity of the enzyme.

Question 8

Substrate concentration

Answer 8

As substrate concentration increases, the rate of reaction increases until all enzyme active sites are occupied (saturation).

Question 9

Enzyme concentration

Answer 9

The reaction rate is directly proportional to the enzyme concentration until a limiting factor is reached (e.g., substrate availability).

Question 10

Inhibitors

Answer 10

Certain molecules can bind to enzymes and inhibit their activity. These can be competitive inhibitors (compete with the substrate for the active site) or non-competitive inhibitors (bind to a different site on the enzyme, altering its shape).

Question 11

Importance of Enzymes

Answer 11

Enzymes are crucial for virtually all biological processes in living organisms. They regulate the rate of metabolic reactions, allowing cells to function efficiently.
Examples include:
Digestive enzymes that break down food molecules in the digestive system.
Respiratory enzymes are involved in cellular respiration for energy production.
Enzymes are involved in building and breaking down molecules for growth, repair, and other cellular processes.