I. Curricular Framework

Concept:

Energy

Essential Question:

Describe the role of a catalyst in a reaction.

Bridge:

Catalysts

Content:

Enzymes

Outcomes:

II. Standards Aligned

III. Instruction and Assessment

1. Connect: Connecting to the Concept Experientially

Objective: To allow the students to become intrigued with a chemical catalyst or enzyme by an initial introduction which compares it to a matchmaker in the movies (or real life).

Activity: The students are shown a clip from the movie Crossing Delancy which is currently available in video rental stores. The clip is about twenty minutes into the film and features an old-fashioned matchmaker who brings a "nice girl" and a "good boy" together. They meet at a kitchen table. While the couple interact, the matchmaker (and the girl's grandmother) leave and go into the kitchen. The connection with enzymes works well, because two substrates (the girl and boy) are brought together so that they can react. They may have gotten together eventually, but it may have taken seventy years. The kitchen table is the active site and the matchmaker leaves and does not become part of the final reaction. The video is timely and currently available, but if it is impossible or impractical to show, this is also the perfect time for the teacher to become storyteller and make up a fascinating five minute story about a kind, nosy neighbor who brings two young people together.

Assessment: Attentiveness of the students during the movie clip or story.

2. Attend: Attending to the Connection

Objective: To have students analyze the role of a matchmaker, guiding them to the aspects that will be appropriate when discussing enzymes.

Activity: As a whole class, students participate in a brief analysis of how a matchmaker "works." The teacher may supply some leading questions such as: "What is the job of a matchmaker?" "Does there need to be a meeting place?" "Does the matchmaker stay around after the couple are happy together?"

Assessment: Quality of class attention and participation

Assessment, Phase One, Level of Engagement, Fascination:

3. Image: Creating a Mental Picture

Objective: To perform a demonstration of a chemical reaction which requires a boost of energy (heat) to happen; to begin the bridge into enzymes which lower activation energy without heat.

Activity: The teacher does a demonstration of a chemical reaction that requires heat in order to occur. A simple and appropriate example might be the Benedict's Test for the presence of glucose. This is an indicator reaction which is commonly used in the average biology class. It is also good because it can be used again in a lab experience as a test for the action of an enzyme. After the demonstration, the students are asked to draw the set up and indicate with color pencils what happened.

Assessment: Success of the students in observing and understanding the role of heat in supplying energy for a reaction to happen.

Assessment, Phase Two, Seeing the Big Picture:

4. Inform: Receiving Facts & Knowledge

Objective: To teach the structure and function of enzymes in lowering activation energy so that substrates can be joined or separated in a chemical reaction without the addition of heat.

Activity: The students need to answer some questions. 1) What is heat? 2) What does heat provide for this reaction? 3) How was heat like a matchmaker? 4) What is the physical color change an indication of? 5) Can a reaction that needs a boost always make use of heat? At this point the teacher introduces the concept of a catalyst or enzyme, defining the action of bond breaking and forming, activation energy, substrates, end products, specificity, active site. During these potentially abstract concepts, it is helpful to use visual aids. Most traditionally, enzymes are described as lock and keys or puzzle pieces. Cut out large puzzle pieces from different color poster boards or actually take your key and fit it in the classroom door, then take someone else's house key and try it. What makes a key specific is its shape. Enzymes are proteins that also have a specific shape. If something de-shapes the enzyme, it doesn't fit anymore.

Assessment: A short quiz on enzyme structure and function.

Assessment, Phase Three, Success with Acquiring Knowledge:

5. Practice: Developing Skills

Objective: To have the students practice their understanding of enzymes through paper problem analysis and actual lab experimentation.

Activity: Students work on practice sheets which consist of varied experimental situations involving the use of enzymes. They get together in small groups to discuss and compare answers. At this point, it is also good for the students to actually try some experimentation which indirectly shows that action of an enzyme on a substrate. Many books use the example of sucrase acting on sucrose to facilitate its breakdown into glucose and fructose. Yeast cells make sucrase. A few grains or a small piece of yeast can stand in a cup of water for about twenty min. Then it should be filtered and the filtrate kept. The filtrate has the enzyme sucrase. To check for the presence of sucrase, the students fill two test tubes 1/4 full of sugar solution. Test one with Benedict's solution for the presence of glucose. Put out 6ml of the enzyme extract in the second tube. Let it set for an hour and test it with Benedict's; it will be positive showing sucrose was changed to glucose and fructose. The students can write a formal lab or do a flow chart of what took place or draw it in terms of a metaphor like the puzzle pieces.

Assessment: Quality of student work on problem situation sheets and lab activity.

Assessment, Phase Four, Success with Acquiring Skills:

6. Extend: Extending Learning to the Outside World

Objective: To have the students take what they have learned about enzymes and apply it in a creative way that capitalizes on their understanding.

Activity: Working in groups of five, the students generate a list of everyday products which they know or suspect use enzymes. Detergents and contact lense cleansers are obvious and excellent examples. One large whole-class list is compiled and different students volunteer to write to some of the different manufacturers of the products for information on the enzyme activity, and if possible, the process used to test for it. While waiting for the manufacturing companies to respond, the groups are given, in class, one lab period to design a new commercial/advertisement for a product of their choice in which the role of the enzymes is emphasized. The commercial should have a brief segment which explains to the public what an enzyme is. Out of class time may be used to actually video the commercial or if it's for a magazine, the layout can possibly be done on a desktop publishing computer. This project allows for a variety of talents: writing, drawing, video-making, computer expertise, acting to be utilized.

Assessment: Diligence, progress, and involvement of each member of the group in working on the commercial.

7. Refine: Refining the Extension

Objective: To have the students evaluate their progress and quality of work with the teacher and each other.

Activity: The groups check in with each other and the teacher to confirm the accuracy of their commercials/advertisements as far as the enzyme information is concerned and to have any "technical" questions answered.

Assessment: Students' ability to complete and critique their project.

8. Perform: Creative Manifestation of Material Learned

Objective: To have the students share their commercials/advertisements.

Activity: Advertisements are displayed and commercials are shown. An “Emzy Award” is presented for the best in each medium. An award can be given for most creative, most accurate, best layout, best video.

Assessment: Quality of student presentation.

Assessment, Phase Five,Performance, Creative Use of Material Learned: