Enzymes & Digestion 2-4 (pgs 52 – 53); 30-2 ( ); 30-3 ( )

What role do enzymes play in living things? 2-4 (pgs 52 – 53); 30-2 ( ); 30-3 ( )  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

 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

Enzyme-substrate Complex hill.com/sites/ /student_view0/chapter2/animation__how_enzymes_work.html

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)

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

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

amylase pepsin

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

Lipase maltase sucrase lactase

Obtaining Macromolecules thru the Food Pyramid