2. Enzymes

3. Enzymes Enzymes: are proteins made of amino acids.Enzymes: are proteins made of amino acids. -Catalyst: they speed up chemical reactions & lower the activation energy. -Catalyst: they speed up chemical reactions & lower the activation energy. -Reusable: remain unchanged after the reaction -specific: there is a perfect enzyme for a certain substrate

4. Are Enzymes reusable? Yes or NO

5. Enzymes are….. A. A. Nucleic Acids B. B. Carbohydrates C. C. Proteins D. D. Lipids

6. Enzymes 3D shape3D shape can be destroyed & denatured (change shape) with extreme changes in pH & temperaturecan be destroyed & denatured (change shape) with extreme changes in pH & temperature have active sites = places where substrate (food & waste) molecules attachhave active sites = places where substrate (food & waste) molecules attach

8. Examples of Enzymes Catalase  breaks down hydrogen peroxide (waste produced in cells) into water and oxygen 2H 2 O 2 ----> 2H 2 O + O 2 Lactase  breaks down lactose in milk Lactase  breaks down lactose in milk Protease  breaks down proteins Protease  breaks down proteins Lipase  breaks down lipids Lipase  breaks down lipids

9. How Enzymes Work? Active sites on enzymes = places where a specific substrate bindsActive sites on enzymes = places where a specific substrate binds Enzyme-substrate complexes form (when substrates attach to active sites on the enzymes) to break apart or put together substances at a fast rateEnzyme-substrate complexes form (when substrates attach to active sites on the enzymes) to break apart or put together substances at a fast rate E+ S  ES  E + PE+ S  ES  E + P

10. What are active sites?

11. Two Model of Enzymes 1. lock & key model → substrate & the enzyme fit together perfectly 2. induced-fit model → enzymes change shape slightly to accommodate the substrate

12. Lock & Key Model

13. Induced-Fit Model

14. Factors Affecting Enzyme Action Temperature – enzymes work best at certain temperatures Temperature – enzymes work best at certain temperatures (– 37 o C is best for human enzymes in the body) (– 37 o C is best for human enzymes in the body) pH – enzymes work best at certain pH; basic, neutral, and/or acidic environments pH – enzymes work best at certain pH; basic, neutral, and/or acidic environments ex.) Amylase in saliva at pH 7, ex.) Amylase in saliva at pH 7, Pepsin in the stomach at pH 2-3, Trypsin in the intestines at pH 9

15. 37° Temperature temperature reaction rate What’s happening here?! human enzymes

16. 7 pH pH reaction rate 20134568910 stomach pepsin intestines trypsin What’s happening here?! 11121314

17. Substrate & enzyme concentrations – how fast reactions take place depends on how much of the substrate & enzyme is available. Substrate & enzyme concentrations – how fast reactions take place depends on how much of the substrate & enzyme is available. Coenzymes – helpers such as vitamins & minerals Coenzymes – helpers such as vitamins & minerals Other Factors Affecting Enzyme Action