Enzymes and Chemical Reactions

1. Enzymes and Chemical Reactions Chapter 2 Section 4 Honors Biology

2. Chemical Reactions • Chemical Reactions – A process that changes, or transforms, one set of chemicals to another • Mass and Energy are conserved • 2 parts to a chemical reaction: reactants and products CO2 + H20  H2CO3 reactant product Reactants enter chemical reaction Products are produced by the chemical reaction

3. Energy in Reactions • Chemical reactions that release energy often occur spontaneously example: magnesium and hydrochloric acid Mg + 2HCl  MgCl2 + H2 energy is not required to start this reaction, it occurs spontaneously • Chemical reactions that absorb energy will not occur without a source of energy being added to the reaction example: magnesium being burned to ash 2Mg + O2  2MgO Energy in the form of heat is required to start this reaction, it does not occur spontaneously

4. Energy in Reactions • In order to stay alive, we have to carry out chemical reactions that require energy • Plants get energy from the sun • Animals get energy from eating plants or other animals that have eaten plants • Not every chemical reaction that releases energy occurs spontaneously (paper will only burn and release light and heat if you strike a match) • The energy required to start a reaction is called activation energy

5. Enzymes • Some chemical reactions occur too slow to make life practical. Cells produce catalysts to help speed things up. • A catalyst is a substance that speeds up the rate of chemical reactions. They work by lowering the amount of energy it takes to start the reaction, the activation energy A catalyst will increase how fast a reaction occurs by lowering the amount of energy it takes to start the reaction

6. Enzymes • Enzymes are proteins (contain N) that serve as biological catalysts. They are found in our cells • They speed up reactions that occur in cells by lowering the activation energy • Enzymes are VERY SPECIFIC, and generally only catalyze one chemical reaction Carbonic abhydrase gets its name because it catalyzes the reaction that removes water from carbonic acid H2CO3  CO2 + H20 What is the reactant? What is the product?

7. Enzymes • Enzymes provide a place for the reaction to occur and the reactants can be brought together to react • The reactants in the enzyme-catalyzed chemical reaction are called the substrates • The place where the substrate bind to is called the active site H2CO3  CO2 + H20 What is the substrate???

8. Enzyme Animation • http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html

9. Factors that Affect Enzmes • Enzymes work like a lock and key. If the lock (enzyme) is changed the key (substrate) will no longer work. • pH and Temperature are 2 factors that will cause an enzyme to no longer work. When the temperature or pH fall too high or too low and the enzyme can no longer work, it is said to be denatured