1. Enzymes The PROTEIN catalyst of life

2. Enzymes…. are protein substances that are necessary for: 1. The chemical reactions that occur in your body. Ex. Pepsin (enzyme) breaks protein down in the stomach. 2. Help to release energy in the form of ATP (adenine tri-phosphate) to the cells

3. 3. Chemical Reactions Reactants- things that start the reaction (what goes in). Products- things that are produced (what comes out).

4. I. Enzyme Vocabulary A. Enzymes end in –ase  Maltase binds to maltose  Lactase binds to lactose  Lipase breaks down fat  Amylase is found in saliva B. Catalyst:  Substance that affects the RATE of a chemical reaction WITHOUT BEING ALTERED  Because it is not altered, can do same thing over, and, over, and, over, and over…….  Enzymes are ORGANIC CATALYSTS

5. Enzyme Vocabulary cont. C. Substrate:  The substance upon which the enzyme reacts D. Active site:  Site where enzyme binds to substrate E. Denature:  When enzyme’s shape is altered due to: high temp strong acids or bases

6. II. How Do Enzymes Work? DEMO 1. The enzyme has an active site which has a on its surface which has a very specific shape. 2. The enzyme and the substrate (what enzymes acts upon) temporarily join together forming the enzyme substrate complex.

7. III. Importance of Enzyme Shape A. Enzymes have specific shapes B. This means enzymes are specific to their substrate C. They will only attach to a substrate that “fits” their shape D. If shape of enzyme is denatured, will it be able to bind to its substrate? NO! E. Two things can cause denaturing: 1. Temperature 2. pH

8. IV. Enzyme-Substrate Complex A. Formed when enzyme binds to substrate B. Very specific

9. C. Lock and Key Model 1.Enzyme-substrate complex often compared to a lock and key. 2. Active site on enzyme can only “FIT” or bind to a specific substrate Example: Amylase will bind to starch, but not cellulose

10. Enzyme-Substrate (ES) Complex (lock and key model) http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html Enzyme is unchanged

12. Bellwork – do this in your journal Tape the Lock and Key Model illustrating an enzyme into your journal. 1. Label the:  Enzyme  Substrate  Active site  Enzyme-substrate complex  product 2. Is this reaction an example of digestion or synthesis? How can you tell?

13. Substrate Enzyme Substrate Products Digestion b/c there are 2 smaller products formed Active Site

14. V. What factors influence Enzyme Action? A. Remember, enzymes speed up reactions B. What can affect the rate at which enzymes perform? 1. It’s shape! a. Denaturing affects rate C. The amount of enzyme and substrate!

15. 1.Temperature - Enzyme shape and reaction rate: a. Enzymes have a specific temperature range at which they work best  EX. Human enzymes work best at 37°C b. Temps not in the optimal range will cause enzymes to denature c. Shape is altered, so reaction rates are SLOWED or stopped altogether

16. d. Reaction rates will DROP dramatically depending on how much denaturing of enzyme Temperature vs. Reaction Rate

17. 2. pH - Enzyme shape and reaction rate: a. Enzymes have a specific pH range at which they work best i. EX. Most enzymes work best at pH 7 ii. Where in the body would enzymes be optimal at a low (acidic) pH? Why? i. In stomach, this is because stomach acid has a low pH b. pH not in the optimal range will cause enzymes to denature c. Shape is altered, so reaction rates are SLOWED or stopped altogether

18. d. Reaction rates will DROP dramatically depending on how much denaturing of enzyme. stomach Small intestine pH vs. Reaction Rate

19. 3. Concentration - Enzyme amount and reaction rate: a. Enzyme rate also depends on the amount of enzyme and substrate b. Little enzyme, lots of substrate: i. Slower rates ii. How can we speed up the rate? 1. Add more enzyme until max. rate achieved. Substrate Concentration vs. Reaction Rate

20. ANSWERS t o RB Topic 2 pages 25-27 #23-40 23) 224) 225) 326) 127) 328) 129) 4 30) 231) 2 32) 333) 3 34) Step 1 – molecule A (enzyme) is combining with molecule B (substrate) Step 2 – enzyme-substrate complex is formed (where digestion will begin) Step 3 - reaction completed and molecules break away; enzyme is unchanged and is able to repeat the process many times again. 35) reaction is digestion (molecule B was broken apart) 36) heating speeds up the reaction BUT excess heat causes the enzyme to denature thereby slowing down or stopping the reaction all together 37) 338) 239) 2 40) No digestion occurred b/c the enzymes are specific (the enzyme present was for protein NOT starch)