What is the function of the human liver?

1. What is the function of the human liver? • Largest gland in the body • Filled with enzymes • Breaks down old worn out red blood cells • Cleans the blood of toxins • Can not survive without a liver

2. Normal Liver

3. Liver with Cancerous Tumors

4. Cirrhosis of the Liver (scarring)

5. ENZYMES What are they and what do they do???

6. What is the importance of enzymes? Enzymes control the rate of reactions within our bodies and cells! Enzymes cause reactions to occur in cells. Enzymes are NEVER changed by the reaction. Enzymes can be used over and over again by the same type of reaction. Enzymes are organic CATALYSTS!

7. What is the structure and Function of Enzymes? • Organisms synthesis the enzymes they need. • All enzymes are PROTEINS! • Enzymes often work with COENZYMES which are made of VITAMINS (if an organism lacks a needed vitamin this can cause a problem with the function of the enzyme)

8. What is an ACTIVE SITE? • The “active site” is the part of the enzyme that is involved with the enzyme action. • Enzyme molecules are usually much larger than the molecules they act upon.

9. What is a Substrate? • A “substrate” is what the enzyme works on!

10. Enzyme-Substrate Complex • Enzyme action takes place when the enzyme-substrate complex forms, causing the reaction to occur. • After the reaction, the enzyme separates from the product or products of the reaction and then act again on other molecules of substrate.

11. Lock and Key • !

12. “Lock and Key” • The shape of the active site of an enzyme molecule fits the shapes of its substrates ONLY! • This is like a key whose shape fits only one lock, and therefore opens only that lock!

13. Enz. + Sub. = Enz-Sub complex + product • !

14. Are enzymes “specific”? • Can enzymes get used up?

15. Can you figure out the enzyme, substrates, and products?

16. Can enzymes last forever? • Although enzyme molecules can be reused many times, they are eventually decomposed in the cell. • The organism must therefore synthesize new enzymes continuously to replace those that are destroyed.

17. Names of Enzymes! • All enzymes end in an “ase” ending! • Their names usually are derived from their substrates. • Example: • Maltase is the enzyme that breaks down maltose.

18. What affects the rate of enzyme action?? • Three factors affecting enzyme action are: • Temperature: • Enzyme action is generally low at low temps, and increases as the temp. rises • If the temp. gets too high the enzyme loses its effectiveness. This is called DENATURATION • The active site no longer fits the substrate. • Ex: when a person gets a very high temperature

19. What affects the rate of enzyme action cont… • pH • A pH scale is a measure of H+ (hydrogen ion) concentration. • pH scale measures from 0 to 14. 0 being extremely acidic, and 14 being extremely basic (alkaline), 7 is neutral (pure water) • Each enzyme acts most effectively within a certain pH range. Ex: pepsin (gastric protease) secreted by stomach works best at a pH of 2 (acidic)

20. What affects the rate of enzyme action cont… • Enzyme substrate concentration • Starting with a given conc. of enzyme and a low conc. Of substrate, the rate of enz. Action incr. as the conc. Of substrate incr. The rate of action incr. up to a point and then levels off as more sub. Is added. It is inferred that at this point all the enz. Mol. Are working at their maximum rate so that an excess of sub. Has no further effect on the rate of action.

21. Let’s draw some diagrams. • 1. enzyme sub complex • 2. enz. Sub conc. sample

22. Can you interpret this graph?

23. What does this graph tell you?

24. What is denaturation? • What causes denaturation and what are the effects?