Enzymes

Enzyme A large protein molecule Specific shape with deep folds on its surface Deep folds form pockets called active site

Enzyme-Substrate The shape of the enzyme active site allows another molecule to fit like a “lock and key” or “puzzle pieces”. This molecule is the substrate and is specific to the enzyme it fits into.

Enzyme-substrate reaction A chemical reaction occurs for the substrate at the active site. The one molecule can be broken down into two or more molecules (decomposition) Or two or more molecules can be made into one larger molecule (synthesis)

Shape of Enzyme is Important If the enzyme environment becomes too hot, the enzyme shape will change Once the shape changes, the substrate will not fit any more Once the active site is no longer the shape of the substrate, the enzyme is no longer functional. The enzyme is now denatured, meaning that it no longer works.

pH can also alter the shape of the active site This enzyme was changed by the environment becoming too acidic.

Enzyme Notes Enzymes are protein molecules. Function depends upon shape. Enzymes speed up chemical reactions. Enzymes lower the amount of activation energy. Enzymes bind to specific substrates at the active site. Enzymes are specific depending upon maintaining shape. Enzymes can become denatured when their shape changes.

Enzyme notes (Continued) If the shape changes, the enzyme can no longer work. Enzyme shape can be affected by changes in temperature or pH. Enzymes are called catalysts because they make the chemical reactions occur faster. Enzyme-substrate is the combination of an enzyme and its substrate at the active site. It may be called a “Lock and Key” model. Enzymes end in “ase” and the prefix relates to the substrate it binds to. Enzymes can either combine or break apart substrates.

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