1. ACTIVITY #13: ENZYMES

2.  Enzyme  Catalyst  Substrate  Activation energy  Active site  Denaturation VOCABULARY

3.  Some chemical reactions would be too slow or have too high of an activation energy without a little help  Catalyst: a substance that speeds up a chemical reaction  Works by lowering the activation energy  Cells make special proteins called enzymes to act as catalysts for chemical reactions  One type of enzyme for each type of chemical reaction  Its shape makes it specific for its job ENZYMES

4. ACTIVATION ENERGY Would the hill be higher or lower with an enzyme present? Lower

5. 1.Provide a site for the reactants to be brought together to react 2.Help to break the bonds of the reactants  Reduces the energy needed for the reaction  “Enzyme Catalyzed Reaction”- a reaction sped up by an enzyme HOW DO ENZYMES WORK?

6.  Substrates- what the reactants are called in an enzyme catalyzed reaction  Bind to a place on the enzyme called the active site which has a specific shape SUBSTRATE

7. 1."Lock and Key Model": substrates fit the active site of an enzyme like a key fits into a lock  A very specific interaction!  Provides the site for the reactants to come together 2 MODELS HELP EXPLAIN HOW ENZYMES WORK Substrate Enzyme

8. 2.“Induced-fit Model”: enzyme binds the substrate(s) and slightly changes its shape to “hug” the substrate(s) tightly (like a handshake)  Places “strain” on existing bonds, allowing bonds to break and the chemical reaction to go forward Example of an enzyme-catalyzed reaction: ____________ is formed by combining ___________________ and water in the presence of the enzyme “_______________________”. Carbonic Acid Carbon dioxide Carbonic anhydrase

9.  After the product is released from the enzyme, the enzyme is recycled and used again  Enzymes are reusable! WHY AREN’T ENZYMES CONSIDERED A REACTANT OR A PRODUCT?

10. 1.protease- any enzyme that speeds hydrolysis or breakdown of proteins 2.sucrase (a disaccharidease) - an enzyme which speeds the breakdown of. 3.lipase - any enzyme which speeds the breakdown of 4.nuclease - any enzyme which speeds the breakdown of 5.amylase - an enzyme which speeds the breakdown of amylose (=starch!) COMMON HYDROLYTIC ENZYMES (THE SUFFIX "–ASE" COMMONLY INDICATES THAT A PROTEIN IS AN ENZYME) Sucrose Lipids Nucleic acids

11.  Temperature, pH, and regulatory molecules affect enzyme activity  An increase in temperature will increase the rate of a reaction to a certain point  After that point, the enzyme will no longer work FACTORS AFFECTING ENZYME ACTIVITY

12.  Denaturation - when a protein unfolds and loses its overall shape (and thus function) due to increased temp or changes in pH  Denatured enzymes lose the shape of their active site and will no longer function DENATURATION Think! Why are temperature and pH important factors in maintaining homeostasis? If they are not maintained then proteins, including enzymes, would denature and chemical reactions could not occur!