Enzymes

Essential Content

A. Enzymes as a catalyst to reduce activation energy (18.11)

1. Activation energy

2. Lock and key model

3. Role as a catalyst

B. Testing the factors affecting Enzyme function (18.11)

1. pH

2. Temperature

3. Concentration

Objectives

· Explain why enzymes are important to living things.

· Describe the primary function of proteins in organisms.

· Explain the role of enzymes and how they speed up the rate of a biochemical reaction by lowering the reaction’s activation energy.

· Test effects of different factors on one or more enzymes.

· Analyze how enzymes speed up the rate of a biochemical reaction by acting as a catalyst and describe the effect of environmental factors on enzyme activity.

· Identify factors, such as pH and temperature, and their effect on enzyme activity.

· Investigate the different effects of different factors on enzyme function within a graph and analyze the data.

Energy in Reactions

Some chemical reactions release energy; others absorb energy.

• Chemical reactions that release energy often occur on their own.

• Chemical reactions that absorb energy require a source of energy. The energy needed to get a reaction started is called the activation energy.

Enzymes

An enzyme is a protein that acts as biological catalyst. A catalyst is a substance that speeds up the rate of a chemical reaction. Catalysts work by lowering a reaction’s activation energy.

• In an enzyme-catalyzed reaction, the reactants are known as substrates. Substrates bind to a part of an enzyme called the active site and remain bound to the enzyme until the reaction is complete, when the products are released.

• Temperature, pH, and regulatory molecules can affect the activity of enzymes.

Tutorial on Enzymes