1. 2.4 Enzymes

2. Changes or transforms one set of substances into another Breaking and Reforming Bonds Example: O 2 + 2 H 2 + energy  2 H 2 O ReactantsProducts Some release energy (exothermic) Some absorb energy (endothermic) Chemical Reactions

3. Require some energy to get things going (to start breaking bonds) All Chemical Reactions….

4. The energy needed to get a reaction started. Some chemical reactions often occur spontaneously. Others that absorb energy cannot occur without a source of energy. Activation Energy

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6. Allow reaction to happen more readily Speeds up the rate of the reaction NOT used up in the reaction Role of Catalysts

7. Proteins that speed up chemical reactions within cells. Example: carbonic anhydrase CO 2 + H 2 O  H 2 CO 3 Converts Carbon Dioxide to Carbonic Acid 10 million times faster than on its own by LOWERING THE ACTIVATION ENERGY NEEDED to complete the reaction Enzymes

8. Brings reactants close together (in correct orientation) so reaction occurs much easier. How Enzymes Work? Active Site is where the substrate bonds to the enzyme

10. The following affect the activity of enzymes : 1. Temperature What do you expect the ideal temperature of activity to be?  (37 degrees Celsius – normal body temperature) 2. pH What effect would pH have on activity? Denature What pH would you expect stomach enzymes (peptidase, lipase) to work most effectively at? – Acidic 3. Regulatory Molecules Bind to enzymes to speed up or slow down their activity by turning them on or off. Regulation of Enzyme Activity

11.   On a separate piece of paper do your best to answer the question (drawings work well!): What role do enzymes play in living things? Minute Paper