Enzymes Chemistry of Living Things

What are we learning? Benchmark: I will explain the role of enzymes as catalysts Objectives: SC.912.L – 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?

What is a catalyst?  The activation energy (E a ) 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 by lowering the activation energy of the reaction. They are used over and over again.  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

Factors that affect Enzymes  Enzymes can be affected by changes in temperature, pH, and concentration of enzyme and substrate molecules. Optimal is the point in which the enzyme works the fastest.  Temperature (optimal temp in humans is 98.6⁰F or 37 ⁰C)  Lower temperature, enzyme works slower  Higher temperature, enzyme works faster  Extreme temperature (boiling, Fever > 106 ⁰F) 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)  Pepsin works best at pH2, its optimal pH  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