Enzymes&

Digestion 2-4 (pgs 52 – 53); 30-2

(868-873); 30-3 (875-881)

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

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

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html

Examples of Enzymes in the Digestive System

amylase breaks down carbohydrates (starch into disaccharides)

pepsin breaks down proteins

lypase breaks 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 hoursmechanical 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

maltasesucraselactase

Obtaining Macromolecules thru the Food Pyramid