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Ch. 19 Carbohydrates

Ch. 19 Carbohydrates. Milbank High School. Chapter Objectives. 1. What are carbohydrates? What is the difference between mono-, di-, and polysaccharides?

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Ch. 19 Carbohydrates

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  1. Ch. 19Carbohydrates Milbank High School

  2. Chapter Objectives • 1.What are carbohydrates? What is the difference between mono-, di-, and polysaccharides? • 2.What are the structures of the most commonly occurring monosaccharides? Be able to classify them as aldoses or ketoses and as trioses, pentoses, or hexoses. • 3.What is the difference between a D and an L sugar?

  3. Chapter Objectives • 4.What is mutarotation? How does it occur? • 5.What are the structures of sucrose, lactose, and maltose, the most common disaccharides? What monosaccharides make up each of these disaccharides? • 6.Compare and contrast starch, glycogen, and cellulose.

  4. What is Biochemistry? • The chemistry of molecules and reactions found in living organisms

  5. Carbohydrates • “Carbon hydrates” • Compounds containing carbon, hydrogen, and oxygen • Starches and fibers (complex carbohydrates) • Sugars • Cellulose • Contain hydroxyl groups • And either an aldehyde or ketone • Known as polyhydroxy aldehydes or ketones

  6. Monosaccharides • Simple carbohydrates • Cannot be further hydrolyzed • Contain 3-7 carbons • Readily dissolve in water • Can link together to form more complex carbohydrates • Disaccharides • Trisaccharides • Polysaccharides

  7. Sec. 19.1General Terminology and Stereochemistry • Named using IUPAC to name monosaccarides • Name the number of carbons, then add -ose • Trios, tetrose, pentose, hexose etc • If aldehyde is attached: aldotetrose • If ketone is attached: ketotetrose

  8. Common monosaccharides • Glucose • Fructose

  9. Enantiomers • Molecules that are nonsuperimposable mirror images of each other • Have identical physical properties except one: • They rotate plane-polarized light in opposite directions

  10. Trioses • Simplest sugars • Two enantiomers • D sugars • L sugars

  11. Sec. 19.2Hexoses • Aldohexoses • 16 isomers (8 enantiomeric pairs) • 3 most common: • Glucose, mannose, galactose • Ketohexoses • 8 isomers • fructose

  12. Glucose • Most abundant sugar in nature • Fruits • “grape sugar” • “Dextrose” b/c it is dextrorotatory • Carbs converted to glucose • Produces energy for our cells • Circulating carbohydrate • Blood sugar

  13. Glucose Con’t • Synthetically made by the hydrolysis of starch • Corn starch • “corn sugar”

  14. Mannose • Component of polysaccharide mannan • Berries • Vegetable ivory “endosperm” • Differs from glucose at only one point

  15. Galactose • Needed by human body for synthesis of lactose • In mammary glands • Also important constituent of the glycolipids • Occur in brain in myelin sheath of nerve cells • “brain sugar” • Differs from glucose at only one point

  16. Fructose • Only naturally occurring ketohexose • Also similar structure to that of glucose • Found in honey (40%) • Formed in prostate gland • Energy source for spermatozoa

  17. Artificial Sweeteners • High-intensity sweeteners • Manufactured in place of mono- and disaccharides • Saccharin • 1890’s • 500-700 times sweeter than sucrose • Carcinogenic

  18. Artificial Sweeteners • Aspartame • 1967 • 160 times sweeter than sucrose • Used in diet soda • Sucralose • 1998 • 600 times sweeter than sucrose • Passes through body unchanged

  19. Sec. 19.3Cyclic Structures of Monosaccharides

  20. Sec. 19.4Properties of Monosaccharides • Crystalline solids at room temperature • Quite soluble in water • Converted to anions when Tollen’s and Benedict’s reagents are used • Used in simple and rapid diagnostic tests for the presence of glucose in blood or urine

  21. Sec. 19.5 Disaccharides • Composed of two monosaccharide units • Joined when one monosaccharide reacts with the hydroxyl group of a second monosaccharide • Forms a carbon-oxygen-carbon linkage • “glycosidic linkage”

  22. Maltose • Occurs in sprouting grain • Forms “malt” in the manufacture of beer • “malt sugar” • About 30% as sweet as sucrose • Body can’t utilize it directly • Must be broken down by enzymes

  23. Lactose • “Milk sugar” • Occurs in the milk of humans, cows, and other mammals • Human milk: 7.5% lactose • Cow’s milk: 4.5% lactose • Synthesized only by mammary tissue in nature • Commercial produced from whey (from cheese) • 1/6th as sweet as sucrose

  24. Lactose Intolerance • People are unable to digest lactose in milk • Need lactase in small intestine to digest it properly • Up to 20% of US population suffer some degree of lactose intolerance • Produces bacteria in colon if not broken down properly • Leads to abdominal distension, cramps, diarrhea

  25. Lactose Intolerance Con’t • Foods can be treated with lactase • Lactaid® • Tablets taken orally with dairy foods to assist in their digestion

  26. Sucrose • “Beet sugar, cane sugar, table sugar, or just sugar” • Largest selling pure organic compound in the world • Obtained from sugar canes and beets • Average American: 100 pounds of sucrose every year

  27. Sucrose Con’t • May cause cancer, heart disease, migraine headaches, hyperactivity in children, obesity, and tooth decay

  28. Sec. 19.6Polysaccharides • Most abundant carbs in nature • Store energy and make up plant cells • High-molar mass • Starch, glycogen, and cellulose

  29. Starch • Most important source of carbs in the human diet • More than 50% of our carb intake • Granule form • Storage • Potatoes: 15% • Wheat: 55% • Corn: 65% • Rice: 75%

  30. Starch Con’t • Mixture of amylose and amylopectin • Amylose: 60-300 glucose units per chain • Amylopectin: 300-6000 glucose units • Commercial starch • White powder • Stamps, envelopes, labels (sticky upon wetting)

  31. Glycogen • “animal starch” • Reserve carb of animals • All mammalian cells contain glycogen • Liver and skeletal cells the most • Used when fasting

  32. Cellulose • Fibrous carb found in all plants • Cell walls • Most abundant of all carbs • Makes up 50% of all carbon in the vegetable world • Much hydrogen bonding…insoluble in water

  33. Cellulose Con’t • Can’t be digested by humans • Herbivores contain special enzymes to digest it and use it for energy • Termites

  34. Dietary Fiber • Insoluble fiber (cellulose) • Reduces risk of colon cancer and heart disease (reduces cholesterol) • ADA recommends 20-35 g a day • Most Americans get 14-15 g a day

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