1. Chemical Reactions and Enzymes

2.  Are processes that change or transform, one set of chemicals into another.  Drive all the activities associated with life.

3.  Involve reactants (starting materials) and products (ending materials).  The atoms of the reactants are rearranged to form the products.

4.  There are two types  Endothermic ▪ Absorb energy ▪ Breakdown macromolecules  Exothermic ▪ Release energy ▪ Build macromolecules

5.  Need some energy to get started  The needed energy is called activation energy. ▪ Activation energy is a chemical push  Is required for both exothermic and endothermic reactions.  Is lowered by enzymes ▪ Enzymes are biological catalysts that speed up chemical reactions, but are not used up by them.

6. Why do enzymes speed up reactions? Enzymes speed up reactions by lowering the activation energy (E a ) of a reaction. The activation energy is the energy needed to start a reaction. Different reactions have different activation energies. reaction (time) energy (kJ) E a with enzyme E a without enzyme

7.  Are large folded proteins that are made of hundreds of amino acids.

8.  All enzymes have active sites  Active sites ▪ Form in the protein folds. ▪ Have a complimentary substrate shape.

9.  Speed up chemical reactions by binding with specific molecules.  The specific molecule is a substrate.  Promote specific chemical reactions

10. http://www.youtube.com/watch?v=V4OPO6J QLOE

11.  Are affected by heat, acidity, and enzyme concentration  Enzymes function with in a certain temperature range.  Enzymes cease to function if the strength of acids in body fluids is too high or too low.  Enzyme concentration determines if a reaction occurs.

12. Enzymes and temperature

13.  Work with a partner to answer questions 1-3 of Assessment 2.4 on page 53 of your Biology textbook. Write the questions and answers in your notebook. Answer the questions thoughtfully and with complete sentences.

14. Enzymes and temperature