Enzymes Standard 1b

Cell Standards 1) The fundamental life processes of plants and animals depend on a variety of chemical reactions that occur in specialized areas of the organism’s cells. As a basis for understanding this concept: ▫b) Students know enzymes are proteins that catalyze biochemical reactions without altering the reaction equilibrium and the activities of enzymes depend on the temperature, ionic conditions, and the pH of the surroundings.

Overview Enzymes are protein catalysts made by living organisms. ▫Catalysts speed up chemical reactions ▫Without enzymes food would look exactly the same at the “other end.”

Structure Enzymes are proteins (long chains of amino acids held together by peptide bonds) They fold into specific 3D shapes determined by the amino acid sequence

Enzymes contain one or more active sites ▫Active site: where one or more substrates bind. ▫Substrate: a molecule that reacts, with the help of an enzyme, to produce new product molecules The enzyme must be the perfect shape or it won’t work!

Action of Enzymes 1.Enzymes bind to specific substrates. 2.The substrate fits into the active site of the enzyme like a lock and key.

3. The enzyme carries out a reaction to make or break bonds in the substrate. ▫lining up molecules so they can react (matchmaker!) ▫putting pressure on bonds to break up molecules (homewrecker!)

4. The reaction produces a product or products.

Enzymes are not used up during the reaction. One enzyme can cause millions of reactions.

Activation Energy Activation energy: the energy required to start a chemical reaction Activation Energy

Example:

Enzymes lower the activation energy necessary for the reaction to happen.

Demonstration of an enzyme in action

Half the steak was placed into the fresh pineapple

After three hours sitting at room temperature

Enzymes are denatured (stop working) when conditions are not right. Factors affecting Enzyme activity

1. Temperature

2. pH (acid & base)

3. Substrate concentration(amount) ▫Few molecules = slow reaction ▫Many molecules = fast reaction