Chemistry of Living Things Enzymes Chemistry of Living Things

What are we learning? Benchmark: Objectives: I will explain the role of enzymes as catalysts SC.912.L.18.11 – Explain the role of enzymes as catalysts that lower the activation energy of biochemical reactions. Identify factors, such as pH and temperature, and their effect on enzyme activity. AA

What Is The Essential Question? Why might an enzyme function incorrectly if its shape were changed? An enzyme and the molecule with which it reacts must fit together. Changing the shape of a protein would prevent it from fitting and thus would affect the function of that protein.

What is a catalyst? The activation energy (Ea) is the energy needed to start a chemical reaction. A catalyst is a substance that increases the rate of a chemical reaction by lowering the activation energy. Catalyst are not used up in the chemical reaction. What is a result of this?

What are enzymes? Enzymes are special PROTEINS that act as biological catalysts by speeding up chemical reactions that take place in cells. The reactants in enzyme-catalyzed reactions are know as substrates. Substrates bind to a part of the enzyme called the active site. The shape of the active site is complementary to the shape of the substrates. “lock and key” model Makes the shape of the protein very important and any change in the amino acid sequence or unfolding of the protein can make the enzyme nonfunctional

Enzyme Reaction Lab

Enzymes are biological catalysts that change the rate of a chemical reaction. For example, 2H2O2  2H2O + O2. This reaction occurs because all living tissues contain the enzyme catalase. Hydrogen peroxide is a harmful by-product of cellular respiration. Cells use enzymes to break down poisonous chemicals very rapidly to prevent a buildup of lethal amounts.

Factors that affect Enzymes Enzymes can be affected by changes in temperature, pH, and concentration of enzyme and substrate molecules. Temperature Lower enzyme works slower Higher enzyme works faster Extreme (boiling, Fever) the enzyme will denature (the protein loses its shape) pH At a higher or lower than normal pH, enzyme will not function because it becomes denatured (the protein loses its shape) Concentration Substrate Higher substrate concentration enzyme will work faster Lower substrate concentration enzyme will work slower Enzyme Higher enzyme concentration, reaction is faster Lower enzyme concentration, reaction is slower