Biochemistry

Lesson 1.3

Enzymes

1.3a. Introduction to Enzymes

1.3.2. Enzyme Overview

Prior Knowledge Fill in the Blank: 

Please read the statements below. What macromolecule goes in each of the blanks: carbohydrate, protein, lipid, or nucleic acid

• Examples of ________________________ are oils and waxes and are used for insulation and long term energy storage.
• Examples of ________________________ are rice, bread, potatoes and sugars, which serve as the main source of energy for living things.
• An example of a ________________________ is an enzyme.The work of the cell is carried out primarily by proteins, most of which are enzymes. Lactase is an enzyme released by the small intestine to break down milk sugar (lactose). They are also found in some soaps and detergents and are used to break down protein, carbohydrate and lipid (oil) stains.

Please read and mark the text below.

If you are unfamiliar with how to mark the text, please read the following instructions:

1. Before reading, please number the paragraphs. (Start with the number one and continue numbering sequentially throughout, placing the number near the start of the paragraph.)
2. Circle key terms and other essential words or numbers.
3. Put a box around any terms you do not know the meaning of or are unfamiliar with.
4. Underline information relevant to the reading purpose

A catalyst is a general term used to describe something that accelerates (speeds up) a chemical reaction. Catalysts speed up reactions by decreasing the activation energy required to start the reaction. Automobiles have catalytic converters that use a catalyst to convert carbon monoxide into carbon dioxide.

Catalysts that function in living organisms are called enzymes. Enzymes are proteins (made up of amino acids) that work in cells as biological/organic catalysts. Enzymes help accelerate (speed up) chemical reactions by lowering the activation energy necessary to start chemical reactions in our own bodies. There are a number of enzymes that help us digest the organic macromolecules found in our food. For example, lactase is an enzyme produced in the small intestine that breaks down its substrate lactose (a disaccharide found in dairy products) into the products glucose and galactose.

Please answer the following questions:

1. Are enzymes catalysts? ______________________________

Explain: _____________________________________________

2. Are all catalysts enzymes? ___________________________

Explain: _____________________________________________

Figure 1.3.3 Enzyme Activation Energy by G. Andruk / Creative Commons Attribution-Share Alike 3.0 Unported

3. Describe the graph in Figure 1.3.3. ___________________________________________________

4. Explain why there are people who are not able to digest lactose. ______________________________________________________

Please see the table below for examples of digestive enzymes. Please fill in the bottom row for lactase:

The locks on your doors are specific and will only work with certain keys. Similarly, enzymes have a very specific 3D shape and will only work with certain substrates. Substrates are molecules that are acted upon by a specific enzyme.

Look at Figure 1.3.4 of an enzyme and substrate below. Imagine the enzyme (blue shape below) is lactase.

1. What is the substrate (orange connected shape below)? _____________________

2. What are the the two products (orange shapes below)? __________________ and ________________

Figure 1.3.4 Enzyme and Substrate by Aejahnke / Creative Commons Attribution-Share Alike 3.0 Unported

Enzymes are not completely used up during a chemical reaction. Instead, enzymes can be used over and over again.

Figure 1.3.5 Enzyme action by Muessig / Creative Commons Attribution-Share Alike 3.0 Unported

Please look at Figure 1.3.5 above.

Please briefly describe the graph using the space below. Is the enzyme completely used up in this reaction? How do you know?

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Please look at Figure 1.3.6.

Please circle the reactants in this equation. Please put a box around the products in this equation. Please label the substrate and the enzyme in this equation.

Figure 1.3.6 Lactase reaction by Psbsub / Creative Commons Attribution-Share Alike 3.0 Unported

Vocabulary Check:

Please fill in the vocabulary table found at the beginning of this lesson for terms 1-2 (definitions and extra practice).