2. Denature proteins Enzymes & Digestion Page 48, 99-105 662-670

3. Protein structure (review) amino acid sequence peptide bonds 1° determined by DNA R groups H bonds R groups hydrophobic interactions disulfide bridges (H & ionic bonds) 3° multiple polypeptides hydrophobic interactions 4° 2°

4. Primary (1°) structure Order of amino acids in chain – amino acid sequence determined by gene (DNA) – slight change in amino acid sequence can affect protein’s structure & its function even just one amino acid change can make all the difference! lysozyme: enzyme in tears & mucus that kills bacteria

5. Sickle cell anemia I’m hydrophilic! But I’m hydrophobic! Just 1 out of 146 amino acids!

6. Protein denaturation Unfolding a protein – conditions that disrupt H bonds, ionic bonds, disulfide bridges temperature pH salinity – alter 2° & 3° structure alter 3-D shape – destroys functionality some proteins can return to their functional shape after denaturation, many cannot In Biology, size doesn’t matter, SHAPE matters!

7. A.Enzymes work best within a certain environment B. Denaturation-Enzymes can be permenantly destroyed by changing their shape! Denaturation is caused by: High temperatures Acidity (pH changes) Solvents (alcohols, like rubbing alcohol) Other chemicals that break the bonds inside the protein that help it keep its shape

8. What role do enzymes play in living things?  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

9.  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

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

11. Examples of Enzymes in the Digestive System amylase breaks down carbohydrates (starch into disaccharides) pepsinbreaks down proteins lypasebreaks down fat maltase, sucrase, lactase Breaks down carbohydrates (disaccharides into monosaccharides)

13. 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

14. 1..Concentration of substrate: 2. Concentration of enzyme Harder for the substrate to randomly find the active site on the enzyme 3.Temperature At higher temperatures molecules move faster, so the substrate has a better chance of finding the active site. Like bumpercars—more collisions when you hit the gas!

15. 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

16. amylase pepsin

17. 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

18. Lipase maltase sucrase lactase

19. Obtaining Macromolecules thru the Food Pyramid