Joanne T. Giordano
William E. Grady Technical-Vocational High School, Brooklyn, NY
August 20, 1998
Summer Research Program for Secondary School Science Teachers
The structure and functions of proteins
Subject: Biology
Grade Level: 9th
Type of Activity: In-class lab.
Topic: Protein structure (To introduce proteins) [9-12 Content Standard C- The cell]
Aim: What do proteins look like? How does their structure affect their function? [Content Standard Unifying Concepts- Form and function]
Main Activity: The structure of proteins has been described by scientists in many different ways, from the sequence of amino acids to how proteins interact. Some of these basic structures of proteins are recognizable: one is the alpha-helix, which looks like an open spiral staircase. Another is the beta-sheet, which resembles a picket fence.
Purpose of Activity:
In the following activity, students will build a model of a protein with four helix units and discuss how this structure might help the protein to do various jobs. [Content Standard Unifying Concepts- Evidence, models, and explanation]
Motivation: (1) How do you use your own shape and movements to accomplish tasks?
What foods contain protein? Why is it important to our survival that we eat proteins?
Do you think you get enough protein in your diet? How can you find out? [9-12 Content Standard F- Personal health]
Motivational Demonstration:
Set a Koosh ball (from a toy store) on a table. Blow on it lightly and ask the class to describe the effect of the moving air on the Koosh ball’s strands. Then give it a quick, hard puff and ask, "How did the strands behave differently when hit by a stronger current of air? How was the overall shape of the Koosh ball affected?" Now stick a small bit of clay on one of the strands and ask students to describe how changes in the form of one of the strands affects the arrangement of the others.
Explain that the Koosh ball’s movements resemble those of a protein molecule, though the two don’t look alike. (In the case of proteins, water, not air, can affect the surface projections of the protein and change its overall shape. This can be elicited from students at the end of the activity.)
Materials: (per group of 4 students):
four 10"-12" carboard tubes (from plastic wrap or aluminum foil)
four 30"-long pieces of Velcro with peel-off sticky back
cotton balls
ping pong or golf ball
Procedure: 1. Arrange students in groups of four. Ask them to write a simple hypothesis about how a protein’s structure might affect its function. Each member of the group will make one helix: Hold one of the tubes vertically and wrap the velcro strip around the tube in a spiral pattern. Attach the cotton balls to the velcro an inch apart from each other. [Content Standard Unifying Concepts- Models]
*Questions: What is the name of the basic protein structure your group just constructed? What do the cotton balls represent?
Position four tubes together so that the cotton balls of one tube touch the velcro strip of another. (They should be able to hold together.)
*Question: What happens if you combine your structure with another group’s?
Now take the ping-pong or golf ball and try to get it into the middle of your four helices.
Follow-up: *Questions:
(1) What do you have to do to get it to fit inside?
(2) How is this similar to what a protein does to accommodate a smaller molecule?
What kinds of molecules change their conformation like this to do their job? [9-12 Content Standard A- Formulate/revise models using evidence]
What are some reasons it might be important for researchers to know the shapes of different proteins?
[9-12 Content Standard A- Identify concepts that guide inquiry]
How do you think they are able to alter a protein’s shape?
(6) What factors in the body’s extracellular environment might affect the shape of a protein?
Conclusion: Have students compare their answers to the above questions (arrived at in their respective groups) to their original hypothesis regarding the relation of protein structure to function. Allow them to write up a conclusion based on the evidence of their "data" from the protein model they constructed which either confirms their hypothesis or revises it. Finally, have the groups compare their findings with each other.
Discussion/Summary:
Have each student group present their conclusions in a brief oral presentation to the class. Encourage debate and questioning among the groups during this process. [Teaching Standard B- Orchestrate scientific discourse] [9-12 Content Standard A- Analyze alternative explanations]
Evaluation: Students will be evaluated based on multiple criteria such as:
how well they followed the given procedures and adhered to the scientific method in structuring their questions and answers;
how well they cooperated with other group members;
the creativity demonstrated in constructing their protein model;
their participation in the follow-up discussion;
the quality of their conclusions in light of their "data".
Follow-up Assignment/Activities:
Students may choose one or more of the following mini-projects as a follow-up homework assignment to the class activity: (Internet or library research is encouraged.)
Design your own protein out of a building set, gumdrops and toothpicks, or a rope or thick string. What do you want your protein to do? How will its shape have to be altered to perform its function?
(2) Investigate why vegetarian diets are often protein deficient. Research vegetarian diets and find out which vegetarian foods can supply humans with an adequate amount of protein either alone or in combinations. Then create a balanced vegetarian menu for a day that would provide you with your daily protein requirements for your age group. [9-12 Content Standard F- Personal health]
Helpful web sites:
Reference: Newton’s Apple 15th Season: Teacher’s Guide, Show #1513. St. Paul, Minnesota, 1998.
[Teaching Standard D- Make accessible technological resources]
Acknowledgements:
Sincerest gratitude is extended to the following persons and institutions for making this summer research program possible and enjoyable for me:
Columbia University's Summer Research Program for Secondary School Science Teachers
Dr. Samuel C. Silverstein, Program Director
Mr. Jay Dubner, Program Coordinator
The Summer Research Program Advisory Committee
Faculty guest speakers from our participating institutions in the Summer Program
The Charles Edison Fund
Drs. John Bilezikian and Stephen Morris, of Columbia University College of Physicians and Surgeons Department of Medicine, Endocrinology
Dr. Hong Gao and Elizabeth Rogorska from Dr. Morris’s lab
PBS Television, Newton’s Apple and their national sponsor, 3M
All of my wonderful, extraordinary colleagues in this program for their inspiration and support.