Enzymes (part 1): Intro to Enzymes

1. Chapter 4 Enzymes

2. Lesson Objectives ? Definition of catalysts ? Definition of enzymes ? Roles of enzymes ? Enzymes found at home ? Characteristics of enzymes

3. BBQ

4. Qn: Why do chefs add pineapple juice/ unripe papaya juice to meat? Qn: What is the purpose of adding the juices? Qn: Can any juice be used for the same function?

5. Marinades ? Tenderizing marinades makes leaner cuts of meat more tender and juicy ? Contents in the marinade that tenderize the meat can come from 1) acidic foods like lemon juice, yogurt, wine, or vinegar OR 2) natural enzymes found in fresh papaya, ginger, pineapple, and figs.

6. What are enzymes? ? Protein in nature (most enzymes!) ? biological catalysts (A catalyst is a substance that alters or speeds up a chemical reaction, without itself being chemically changed at the end of the reaction) ? therefore required in small quantities

7. How do enzymes alter the rate of chemical reactions? ? The energy needed to start a chemical reaction is called activation energy ? Enzymes lower the activation energy required to start a chemical reaction

8. time

9. Terms to know: Enzyme-substrate complex substrate: substances on which enzymes act upon Note the surface configuration/shape of the substrate & enzymes

10. Lock & Key Hypothesis

12. +

13. synthetase hydrolase

14. Based on lock and key hypothesis… Enzymes 1. alter the rates of reaction 2. are specific 3. are required in minute amounts

15. Roles of enzymes 1) digestion 2) synthesis of complex substances 3) hydrolysis of complex substances e.g. hydrolysis by catalase

16. 1) Digestion 3 main classes of food we eat 1. Carbohydrates 2. Proteins 3. Fats Molecules are: Large Insoluble Non-diffusible molecules ? ? ?

17. Digestion Involves breakdown of Carbohydrates ? simple sugars Proteins ? amino acids Fats ? fatty acids + glycerol ? ? ? Brought about by action of digestive enzymes Converted into: small soluble diffusible molecules ? ? ?

18. Carbohydrate Carbohydrates Monosaccharides (simple sugars) Disaccharides (complex sugars) Polysaccharides starch cellulose glycogen e.g. glucose, galactose, fructose e.g. maltose, lactose, sucrose

19. Disaccharides & Monosaccharides Disaccharide Monosaccharide maltase Maltose glucose + glucose lactase Lactose glucose + galactose sucrase Sucrose glucose + fructose

20. Hydrolysis ? Break down of complex molecules into simpler molecules ? Water molecules are needed for the process

21. Enzymes Active site: the substrate binding site of an enzyme The shape of the substrate has to be complementary to the active site for the chemical reaction to take place

22. 2) Synthesis of complex substances (plants) ? Composed entirely of glucose units ? Yet have different properties ? Due to differential arrangement (humans) (plants)

23. 3) Breakdown of complex substances Chemical reactions produce H2O2 H2O2is toxic to tissues Cells produce catalase Catalase breaks down hydrogen peroxide ? water and oxygen

24. Potato + hydrogen peroxide Hydrogen peroxide ? Where is the source of catalase? ? A slice of potato or a drop of blood will cause hydrogen peroxide to fizz (form bubbles) Bubbling in H2O2 source of catalase

25. Classification of enzymes

26. Many classes 1. Hydrolases e.g. digestive enzymes - carbohydrases e.g. amylase (digest starch), cellulase (digest cellulose) - proteases (digest proteins) - lipases (digest fats a.k.a lipids) 2. Oxidation-reduction enzymes