Enzymes & Digestion 2-4 (pgs 52 – 53); 30-2 (868-873); 30-3 (875-881)

1. Enzymes & Digestion 2-4 (pgs 52 – 53); 30-2 (868-873); 30-3 (875-881)

2. What role do enzymes play in living things? 2-4 (pgs 52 – 53); 30-2 (868-873); 30-3 (875-881) • some important chemical reactions are too slow or have a high activation energy (require too much energy to start the reaction) • catalysts – substances that speed up the rates of chemical reactions • enzymes are proteins that act as natural catalysts

3. enzymes are very SPECIFIC, catalyzing only 1 chemical reaction. • enzyme-substrate complex  where reactant (substrate) meets enzyme & enough energy is provided to start the reaction • substrate (reactant) binds to active site on specific enzyme (complimentary fit – like a lock & key) • enzymes remain unchanged

4. Enzyme-substrate Complex http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html

7. Regulation of Enzyme Activity • enzymes can be affected by temperature and pH • enzymes produced by human cells work best at normal human body temperature • stomach enzyme pepsin works best in acidic conditions

8. Digestive System • food travels through many organs of the • digestive system • broken down into usable nutrients • mouth: 1 minute • mechanical digestion via teeth • chemical digestion via amylase • esophagus: 2-3 seconds • tube that leads to the stomach via • peristalsis

9. amylase pepsin

10. stomach: 2-4 hours • mechanical digestion via muscle churning • chemical digestion via pepsin • small intestine: 3-5 hours • bile(made by liver & stored in gall bladder) • chemically breaks down fat along with lipase • enzymes maltase, sucrase, and lactase • break down carbs • large intestine: 10 hrs – several days • absorbs H2O and eliminates wastes

11. Lipase maltase sucrase lactase

12. Obtaining Macromolecules thru the Food Pyramid