Interactive, scaffolded model
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In this activity students discover how the properties of amino acids (charge and polarity) affect the shape of a peptide chain. They explore the complex interactions of amino acids with each other and with the surrounding water molecules or lipids. Sickle Cell Anemia is used as an example of a disease caused by a single amino acid substitution.
Students will be able to:
Using the knowledge you have gained in this activity, how would you explain the effect on a protein's activity of a point mutation in an enzyme? (Point mutation: substitution of one nucleotide in DNA that results in the substitution of one amino acid for another in the resulting protein molecule. This could possibly affect the charge on and the folded shape of the protein molecule.)
Students need assistance in understanding that hydrophobicity is a lack of attraction to the polar water molecules and not a repulsion. The term hydrophobic itself is misleading, because hydrophobic amino acids don't actually repel water. Emphasize the idea that, as water molecules make hydrogen bonds with charged amino acids and with each other, non-polar molecules are pushed or herded away from water.
To help students understand the concept of hydrophobicity, have students look at the model Hydrophobia: Activity #203 in this database.
A peptide chain folds into a specific shape as a result of interactions of amino acids with each other and with the surrounding medium. One concept organization is available at: http://www.concord.org/~btinker/workbench_web/pdfs/Protein_Structure.pdf
Additional Related Concepts
Protein folding is a logical precursor to such activities in the database as:
Insulin (Activity): http://molo.concord.org/database/activities/236.html
Melittin (Demo) Protein: http://molo.concord.org/database/activities/87.html
Hemoglobin Tour: http://molo.concord.org/database/activities/281.html
Docking: Binding of Complementary Surfaces: http://molo.concord.org/database/activities/154.html