biol_1322_ch4

biol_1322_ch4 - The Carbohydrates Chapter 4 Sugars Starches...

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1 The Carbohydrates Chapter 4 Sugars Starches Fiber • Are there good carbs and bad carbs? • What is a “net carb”? • Is eliminating carbohydrates from the diet healthy? What Do You Think? Carbohydrate Functions • Protein sparing • Energy - 4 kcal/gm • Builds glycogen • Antiketogenic • Energy for brain • Fiber - bulking agent • Nucleic acid synthesis The Chemist’s View of Carbohydrates • Composed of carbon, oxygen and hydrogen • Most, but not all, have a ratio of one carbon molecule to one water molecule CH 2 O • Carbo = carbon • Hydrate = with water What Foods Are High in Carbohydrates? • Breads, Grains, Cereals, Pasta, Legumes - provide 15 grams/serving • Fruit - provide 15 grams/serving • Milk/Dairy - provide 12 grams/serving • Vegetables - provide 5 grams/serving • Meat & Fats/Oils - provide 0 grams Carbohydrate Recommendations • RDA for carbohydrate –130 g/day –45% - 65% total daily energy intake • Daily Value: 300 g/day
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2 Carbohydrates •S imp le carbohydrates – Monosaccharides – Disaccharides • Complex carbohydrates –S ta rch –F ibe r –G lycogen Simple Carbohydrates – The Monosaccharides • Monosaccharides –Glucose –Fructose –Galactose Simple Carbohydrates – The Disaccharides •Ma ltose –Glucose + Glucose •Sucrose –Glucose + Fructose •Lactose –Glucose + Galactose Complex Carbohydrates • Polysaccharides –Glycogen –Starches –Fibers Fibers – Complex Carbohydrates •F i b e r s – Cellulose – Hemicelluloses –L i gn in –P e c t s –Gum s – Mucilages • Differ from starch b/c the glucose units are connected by beta 1-4 linkages; starch contains glucose units that are connected by alpha 1-4 linkages • Amylase only works on the alpha 1-4 bonds, not beta 1-4 bonds Digestion of Carbohydrate • Mouth • Salivary amylase is secreted in the saliva and begins to break down starch only, not simple sugars • The longer the starch remains in the mouth, the more digestive action that takes place by the amylase enzyme t a r c h –am y l a s e Smaller Polysaccharides - amylase Dextrins - amylase Maltose
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3 Digestion of Carbohydrate (cont.) • Stomach • Mixing/Churning • Starches and other simple sugars are swallowed and the amylase enzyme is deactivated once it comes into contact with the hydrochloric acid • No stomach amylase enzyme is produced to continue starch digestion • Fibers linger in stomach delaying gastric emptying Digestion of Carbohydrate (cont.) • Small Intestine • Pancreas produces pancreatic amylase • Pancreatic amylase – breaks down large polysaccharides into maltose polysaccharides (starch & dextrins) disaccharides (maltose) • Brush border enzymes breakdown disaccharides into monosaccharides (see next slide)
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This note was uploaded on 11/26/2009 for the course BIOL 1200 taught by Professor Ru during the Spring '09 term at Zion Bible.

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biol_1322_ch4 - The Carbohydrates Chapter 4 Sugars Starches...

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