Everything About Enzymes!! (and a free lab!)

Recently, I was required to attend a system-wide inservice meeting for all the science teachers in our district.  In attendance were science teachers of grades 7 through 12.  These events are fun and interesting, mostly because I have been teaching for 28 years, and it is nice to see science teachers from other schools that I have known for years, but rarely get to see.  After joining up with a group of old acquaintances, the inevitable question came up:  "What have you been doing in your biology classes?"

I responded with, "I have just finished teaching a unit on enzymes to our biology 1 students."  One of the other teachers immediately responded with, "I don't really teach that in my class."

What????  How do you NOT teach about enzymes in a biology class????  As soon as I returned home that day, I promptly sent her all of my teaching materials on enzymes.

Enzymes are the stuff of life.  No cell would be alive without the action of enzymes.  Life in a cell is made possible through the hundreds of chemical reactions that occur there.  If these chemical reactions proceed too slowly, the activities of the cell would come to a screeching halt.  You see, enzymes are biological catalysts. They speed up the chemical reactions of the cell.  Without these enzymes, the reactions of the cell would proceed so slowly that they would be of no use to the cell, and the cell would die.

When is the best time to teach about enzymes?  I begin teaching about enzymes when I teach biochemistry.  When teaching about carbohydrates, lipids, and proteins, it is a natural fit to talk about enzymes as you discuss the structure and functioning of proteins.  I also teach about enzymes when I cover photosynthesis, respiration, replication, transcription, digestion..... This list could go on and on since enzymes are involved in every single biological process!

Be sure to cover all the basic points about enzymes:

• Enzymes are biological catalysts that speed up the chemical reactions of the cell.
• Enzymes are proteins.
• Enzymatic reactions occur faster and at lower temperatures because enzymes lower the activation energy for that chemical reaction.
• Enzymes are never consumed or used up during the reaction. They can do their job over and over again.

• Enzymes are highly specific for just one substrate.  The enzyme has an active site with a unique 3-D shape into which this substrate must fit.  
• Enzymes catalyze both the forward and the reverse of the same reaction.
• Enzymes can be denatured by temperatures and pH levels outside the optimal range for that particular enzyme.

Enzymes are truly amazing proteins that play a vital role inside every living cell.  Please don't leave this out of your curriculum!

Okay.... I did promise you a freebie.  This is a lab that I have done for years, and it remains a favorite with my students year after year.

FREE LAB:

Enzymes Common to Both Plants and Animals

And if you are interested, here are a few other products that I use when teaching about enzymes:

Enzymes, Catalysts, and the Chemical Reactions of the Cell Complete Teaching Bundle of Products
Enzymes and Catalysts PowerPoint with Notes for Teacher and Student
Lab: The Effect of Amylase on Starch

FREE LAB! Catalase - An Enzyme Common to Both Plants and Animals

We all have our favorite labs, and this enzyme lab is one of my very favorites.  I love this lab because my students come away with a much better understanding of how enzymes do their important jobs within cells.  Students love this lab because ... well just look at the picture to the left.  

What concepts are covered/reinforced?

1.  Enzymes speed up the rate of biological chemical reactions.

2.  The same enzymes are found in both plant and animal cells.

3.  Enzymes are highly specific for the reaction they catalyze.

4.  Enzymes carry out their functions more efficiently than catalysts.

5.  Enzymes can be denatured by excessive heat.

Introduction:  Catalase is an enzyme that is commonly found in plant and animal tissues.  The function of the enzyme catalase is to break down the chemical hydrogen peroxide inside living cells.  Hydrogen peroxide (H₂O₂) is a highly active chemical, often used for bleaching.  

Within cells, hydrogen peroxide is thought to be formed continually as an end product of biochemical reactions such as cellular respiration.  Because it is toxic, or poisonous, it would soon kill the cell if it were not removed or broken down immediately.   Therefore, the catalase found in living cells protects the cell by breaking down or digesting this poisonous hydrogen peroxide into water and oxygen. 

Manganese dioxide is a catalyst.  Catalysts are similar to enzymes in that they speed up chemical reactions, but they are not specific for just one reaction.  

Materials needed:

• Fresh plant and animal tissue (Potato and Liver)
• Boiled animal tissue (Liver)
• 3% hydrogen peroxide
• Manganese dioxide
• Test tubes and test tube rack
• Sand
• Mortar and pestle

Catalase is an enzyme that is found in all eukaryotic cells.  This lab will work using any fresh and living tissue.  I always use liver as a source of animal cells that contain catalase, and potatoes as a source of plant cells that contain catalase.  I purchase the liver frozen at the grocery store.  When thawed, it works perfect!  Often I will also use a yeast solution to show that fungal cells contain the same enzyme.

What reaction will students see as catalase breaks down the hydrogen peroxide?

As you can imagine, students absolutely love this lab!!  Click the link below to download this free lab.  Enjoy!

Catalase: An Enzyme Common to Both Plants and Animals

Also related:

Enzyme Lab: The Effect of pH on Living Cells

Enzymes: Complete Unit Bundle

Enzyme Graphing Activity

Lab: The Effect of the Enzyme Amylase on Starch

Enzymes Task Cards

The Effect of the Enzyme Amylase on Starch

This is a fun lab that students enjoy and it teaches important concepts about enzymes.

Make your biology class more appealing and exciting by incorporating a variety of fun and interesting labs into your weekly lesson plans.  This inquiry-based lab allows students to discover basic information about the functioning of enzymes within cells.  Enzymes are biological catalysts that speed up the chemical reactions within cells.  Without the aid of enzymes, the chemical reactions of the body would proceed so slow that the reaction would be of no use to the cell.

Purpose:  In this lab, the student will observe the effect of the enzyme amylase on its substrate, starch.  The student will perform various experiments with the enzyme amylase and will compile a list of facts concerning enzymes.

Students are given the task of trying to determine what happens to starch in the presence of the enzyme amylase.  There are essentially four mini-experiments in the lab that will lead the student to the appropriate conclusion.

1. The student mixes together a solution of of amylase and starch and determines the length of time it will take until the starch has been completely broken down into end products.  This is done by removing a drop of the solution each minute and testing it for the presence of starch.
2. Now the student must determine the end products of the reaction.  Benedict's solution is used in this second portion of the lab to determine that the end product is a simple sugar.
3. In the third portion of the experiment, students use glucose test strips to determine that glucose is NOT one of the end products.
4. Finally, the student will test the solution for the presence of proteins to determine that the enzyme is still present when the reaction is complete.

This lab is designed for a typical high school biology class for students in grades 9 – 12.  It is appropriate for both standard and honors classes as well as for first or second year biology students.  I have used this lab in both my freshman biology I class as well as my AP biology class.

Happy Teaching!