Enzymes

1. Enzymes Enzymes a Fun Introduction http://www.youtube.com/watch?v=XTUm-75-PL4&safe=active Enzymes: what they are http://www.youtube.com/watch?v=hoBhOdQV7vw&safe=active Enzyme Function http://www.youtube.com/watch?v=E-_r3omrnxw&feature=rellist&playnext=1&list=PLC7ZMTERKSOJO48-GKSQYXM6Z0YH-ZBLG&safe=active

2. Enzymes and Chemical Reactions • To function properly, cells must carry out thousands of chemical reactions • All chemical reactions require energy

3. Activation Energy: the initial push of energy to get a chemical reaction started

4. Enzymes lower the activation energy needed to begin a reaction

5. Enzymes • Large complex protein molecules • Organic Catalysts: speed up the rate of chemical reaction in living things • Rate of Reaction: how quickly product is produced over time

6. Enzymes are not chemically changed by a reaction, so they can be reused over and over by the cell. • You only need a small amount of enzyme to catalyze thousands of reactions each second.

7. Enzymes often work with co-enzymes (non-proteins like vitamins).

8. Making Enzymes: • Protein molecules synthesized at ribosomes • Most used within cells • Some passed out of cell (secreted) to catalyze reactions outside cell • Ex: Digestive Enzymes

9. Enzymes are Specific: • Can only work with one specific substrate • Specificity is due to shape • If shape is altered for some reason, enzyme will not function properly

10. Active Site: location on enzyme where substrate binds and reacts

11. Lock and Key Model Enzyme binds with a specific substrate at active site. (like key in lock)

12. Enzyme substrate complex forms • Reaction takes place • Substrate gets altered. • Products get released • Enzyme can go on to react with more substrate.

13. Induced Fit Model: (flexible enzyme) • Substrate and enzyme may not fit exactly. • When substrate joins, the enzyme changes shape slightly making the fit more exact. (flexible lock)

14. Note: • Certain metabolic genetic disorders involve a single amino acid in an enzyme being changed. • The enzyme shape is altered and it cannot function properly • Ex: • Sickle Cell Anemia

15. Names of Enzymes: • Start with beginning of substrates name • End in “-ase” • Ex: • Protease – enzyme reacts with proteins • Lipase – enzyme reacts with lipids • Sucrase – enzyme reacts with sucrose (disaccharide)

16. Factors Influencing Enzyme Action • Temperature • pH levels • Concentration of Available Substrate

17. Changing Temperature • For most enzymes in humans, the optimum temp. to function properly is about 98.6°F (37°C)

18. If too cold – reaction slow • As it heats up - reaction speeds up • If too high - reaction stops, enzyme denatures

19. Denaturation • At temp. above or below the optimum, the enzyme starts to lose its shape and stops functioning. • Active site no longer fits substrate Enzyme has Denatured

20. Biologist Pick Up Line

21. Different organisms have different optimum temp. for enzyme activity

22. Changing pH Levels • Each enzyme has an optimum pH at which it functions best.

23. Ex: Digestive Enzymes Pepsin: works in stomach (acidic pH) Trypsin: works in small intestine (slightly basic pH) Salivary Amalase: works in mouth (neutral pH)

24. What is the optimum pH for each of these enzymes to function?

25. Changing Concentration of Substrate • As concentration of available substrate increases, more is available to react with enzyme so rate of reaction increases.

26. Eventually rate of reaction will level off as available enzymes are all being used. (point of enzyme saturation)