Academic journal article The American Biology Teacher

Simulation & Demonstration: The Nature of Enzymes & How They Are Denatured

Academic journal article The American Biology Teacher

Simulation & Demonstration: The Nature of Enzymes & How They Are Denatured

Article excerpt

After students learn about the characteristics of life, including the meaning of the term metabolism; hydrogen bonds; and organic macromolecules, including globular shaped proteins; introduce them to enzymes.

Begin by having them define the word "catalyst." Some will say that they are chemical agents that speed up chemical reactions. Tell them that most of the thousands of different enzymes found in living organisms are globular protein molecules that function as organic catalysts and permit thousands of different metabolic reactions to proceed at rates that sustain life. Students learn about certain properties of enzymes such as: active sites, interactions with substrates, specificity for substrates, and the upper limits of temperature imposed upon their catalytic activities.

Ask the class to imagine an infant with a prolonged body temperature of over 44[degrees] C resulting from being left in a closed van on a hot summer day. * When asked about the fate of this child, students readily note that such cases are generally fatal, however, a causal explanation for this death, other than "heat kills," may not be as forthcoming.

Remind the class that energy transferring metabolic activity is one of life's defining characteristics. Tell them that the enzymes of individuals with internal body temperatures significantly greater than the normal 37[degrees] C are irreversibly inactivated through changes in their shapes. The resulting molecules are said to be denatured. Explain that the chemical basis for denaturation resides within the three levels of enzyme structure.

A simple and inexpensive model simulating an enzyme's structural organization and denaturation can be built and used as follows.

Materials

* a partially-coiled telephone or computer keyboard extension cord

* a thin rubber band

* a small piece of lined paper folded into a wedge

* scissors

Procedure

Explain that the uncoiled portion of the cord (see Figure 1) represents the primary structural level of a protein molecule and consists of a chain of amino acids linked by covalent bonds. …

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