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Carbohydrates function
- 1. The Carbohydrates 1Ahmed Hassan fb/A7med1Hassan Ahmed Hassan fb/A7med1Hassan
- 3. The Chemist’s View of Carbohydrates • The term carbohydrate is derived from the French: hydrate de Carbone • Carbohydrates consist of the elements Carbon (C), Hydrogen (H) and Oxygen (O) with a ratio of hydrogen twice that of carbon and oxygen. • Empirical formula: Cx(H2O)y and All have C=O and -OH functional groups. 3Ahmed Hassan fb/A7med1Hassan
- 4. Types of Carbohydrates Simple Carbohydrates monosaccharides Disaccharides Complex Carbohydrates oligosaccharides polysaccharides • glycogen • starches 4Ahmed Hassan fb/A7med1Hassan
- 5. The Simple Carbohydrates • Monosaccharrides are single sugars (most are hexoses). Glucose serves as the essential energy source, and is commonly known as blood sugar or dextrose. Fructose is the sweetest, occurs naturally in honey and fruits, and is added to many foods in the form of high-fructose corn syrup. Galactose rarely occurs naturally as a single sugar. 5Ahmed Hassan fb/A7med1Hassan
- 7. D-glucose • Glucose is an aldohexose sugar. • Common names include dextrose, grape sugar, blood sugar. • Most important sugar in our diet. • Most abundant organic compound found in nature. • Level in blood can be as high as 0.1% C C C C C CH2OH OH OH H OHH HO H H OH 7Ahmed Hassan fb/A7med1Hassan
- 8. D-fructose • Another common sugar. • It is a ketohexose. • Sweetest of all sugars. CH2OH | C=O | HO-C-H | H-C-OH | H-C-OH | CH2OH 8Ahmed Hassan fb/A7med1Hassan
- 9. D-ribose • An important sugar used in genetic material. This sugar is not used as an energy source but is a part of the backbone of RNA. When the C-2 OH is removed, the sugar becomes deoxyribose which is used in the backbone of DNA. H | C=O | H-C-OH | H-C-OH | H-C-OH | CH2OH 9Ahmed Hassan fb/A7med1Hassan
- 10. The Simple Carbohydrates • Disaccharides are pairs of monosaccharides, one of which is always glucose Condensation reactions link monosaccharides together. Hydrolysis reactions split molecules and commonly occur during digestion. Maltose (Malt sugar) consists of two glucose units. It is not common in nature except during the germination of seeds and fermentation. Sucrose is fructose and glucose combined. It is refined from sugarcane and sugar beets, tastes sweet, and is readily available. Lactose is galactose and glucose combined. It is found in milk and milk products. 10Ahmed Hassan fb/A7med1Hassan
- 12. Lactose • Milk sugar - dimer of -D-galactose and either the or - D-glucose. -Lactose OOH H H H H OH CH2OH H OH OH OH H H H OH CH2OH H OH O -D-galactose -D-glucose (1 4) linkage, disaccharide. 12Ahmed Hassan fb/A7med1Hassan
- 13. Lactose • We can’t directly use galactose. It must be converted to a form of glucose. • Galactosemia - absence of needed enzymes needed for conversion. • Build up of galactose or a metabolite like dulcitol (galactitol) causes toxic effects. • Can lead to retardation, cataracts, death. 13Ahmed Hassan fb/A7med1Hassan
- 14. D-glucose vs. D-galactose C C C C C CH2OH OH OH H OHH HO H H OH O C C C C C CH2OH OH H H OHH HO HO H H D-glucose D-galactose Can you find a difference? Your body can! You can’t digest galactose - it must be converted to glucose first. 14Ahmed Hassan fb/A7med1Hassan
- 15. Sucrose • Table sugar - most common sugar in all plants. • Sugar cane and beet, are up to 20% by mass sucrose. • Disaccharide of - glucose and - fructose. (1 2) linkage CH2OH O CH2OHH OH H H OH H O OH H H OHH OH CH2OH H O 15Ahmed Hassan fb/A7med1Hassan
- 17. 17 How sweet it is! Sweetness relative Sugar to sucrose lactose 0.16 galactose 0.32 maltose 0.33 sucrose 1.00 fructose 1.73 aspartame 180 saccharin 450 Ahmed Hassan fb/A7med1Hassan
- 18. The Complex Carbohydrates • Few (oligosaccharides) or many (polysaccharides) glucose units bound/linked together in straight or branched chains. 18Ahmed Hassan fb/A7med1Hassan
- 19. Polysaccharides • Carbohydrate polymers • Storage Polysaccharides • Energy storage - starch and glycogen • Structural Polysaccharides • Used to provide protective walls or lubricative coating to cells - cellulose and mucopolysaccharides. 19Ahmed Hassan fb/A7med1Hassan
- 20. The Complex Carbohydrates • Glycogen Storage form of glucose in the body Stored in liver and muscles as granules. Provides a rapid release of energy when needed • Starches Storage form of glucose in plants Found in grains, tubers, and legumes 20Ahmed Hassan fb/A7med1Hassan
- 21. Fig. 4-8, p. 106 Starch (amylopectin) Starch (amylose)Glycogen A Glycogen molecule contains hundreds of glucose units in highly branched chains. Each new glycogen molecule needs a special protein for the attachment of the first glucose (shown here in red). A Starch molecule contains hundreds of glucose molecules in either occasionally branched chains (amylopectin) or unbranched chains (amylose). Stepped Art21Ahmed Hassan fb/A7med1Hassan
- 22. Glucose in the Body • A Preview of Carbohydrate Metabolism The body stores glucose as glycogen in liver and muscle cells. The body uses glucose for energy if glycogen stores are available. If glycogen stores are depleted, the body makes glucose from protein. • Gluconeogenesis is the conversion of protein to glucose. • Protein-sparing action is having adequate carbohydrate in the diet to prevent the breakdown of protein for energy. 22Ahmed Hassan fb/A7med1Hassan
- 23. Glucose in the Body • The Constancy of Blood Glucose Maintaining Glucose Homeostasis • Low blood glucose may cause dizziness and weakness. • High blood glucose may cause fatigue. • Extreme fluctuations can be fatal. 23Ahmed Hassan fb/A7med1Hassan
- 24. Glucose in the Body • The Constancy of Blood Glucose The Regulating Hormones • Insulin moves glucose into the cells and helps to lower blood sugar levels. • Glucagon brings glucose out of storage and raises blood sugar levels. • Epinephrine acts quickly to bring glucose out of storage during times of stress. Balance glucose within the normal range by eating balanced meals regularly with adequate complex carbohydrates. Blood glucose can fall outside the normal range with hypoglycemia or diabetes. 24Ahmed Hassan fb/A7med1Hassan
- 26. Glucose in the Body • The Constancy of Blood Glucose Diabetes • Type 1 diabetes is the less common type with no insulin produced by the body. • Type 2 diabetes is the more common type where fat cells resist insulin. • Prediabetes is blood glucose that is higher than normal but below the diagnosis of diabetes. Hypoglycemia is low blood glucose and can often be controlled by dietary changes. 26Ahmed Hassan fb/A7med1Hassan