Lecture 19 Wednesday 3/22/17

DISACCHARIDES A is identified by: Disaccharides are two monosaccharide units linked together by acetal or ketal A is identified by: the numbers associated with the carbon atoms joined together by the linkage. the configuration of the linkage for any anomeric carbon atom joined by the linkage.

IMPORTANT DISACCHARIDES Maltose is: malt sugar. formed during the digestion of starch to glucose. found in germinating grain. a hemiacetal, hydrolyzed to form two molecules of D-glucose.

IMPORTANT DISACCHARIDES (continued) Lactose is: milk sugar (5% cow milk, 7% human milk by weight). composed of galactose and glucose units joined by a hemiacetal, which means lactose is a

IMPORTANT DISACCHARIDES (continued) Sucrose is: common household sugar. composed of fructose and glucose units joined by found in many plants (especially sugar cane and sugar beets). hydrolyzed to produce invert sugar (a mixture of equal amounts glucose and fructose).

IMPORTANT DISACCHARIDES (continued)

IMPORTANT DISACCHARIDES (continued)

POLYSACCHARIDES Polysaccharides are condensation polymers containing thousands of units. They are They can form thick colloidal dispersions when heated in water. Starch is used as a thickener in sauces, gravies, pie fillings, and other food preparations.

IMPORTANT POLYSACCHARIDES Starch is: a polymer consisting of a form of D-glucose in plants. one of two forms, which are: unbranched amylose (10-20%), which is composed of 1000-2000 glucose units with

IMPORTANT POLYSACCHARIDES (continued) and branched amylopectin (80-90%)

IMPORTANT POLYSACCHARIDES (continued) Amylose complexes with iodine to form a dark blue color. The molecular conformation of starch and the starch-iodine complex: (a) the helical conformation of the amylose chain and (b) the starch-iodine complex.

IMPORTANT POLYSACCHARIDES (continued) Glycogen (animal starch) is: a polymer used by animals to store glucose, especially in the liver and muscles.

IMPORTANT POLYSACCHARIDES (continued) Cellulose is: a polymer of the most important structural polysaccharide. the most abundant organic compound on earth. found in a linear polymer like amylose, but has not easily digested and a constituent of dietary

IMPORTANT POLYSACCHARIDES (continued) Cellulose structure:

IMPORTANT FUNCTIONS OF LIPIDS coatings found on some plants compounds with low densities form of energy for plants and animals components, especially in cellular membrane formation

LIPID CLASSIFICATION (continued) Saponifiable lipids contain an ester that can undergo basic hydrolysis. contain one or more fatty acids and an alcohol. are ester-containing lipids with more than two types of components: an alcohol, fatty acids, and other components. lipids do not contain an ester and cannot be hydrolyzed.

LIPID CLASSIFICATION Lipids are biological compounds that are soluble only in nonpolar solvents.

FATTY ACIDS Fatty acids: are the building blocks of many lipids. have long responsible for fatty/oily characteristics. The carboxyl group is very under conditions of physiological pH

FATTY ACIDS (continued) In water, fatty acids will form spherical clusters called are important for biological functions, like the transport of insoluble lipids in the blood.

FATTY ACIDS (continued) Fatty acids are: usually straight chains (no branching). usually from usually an number of carbons. either saturated or unsaturated

FATTY ACIDS (continued) Examples of saturated, monounsaturated, and polyunsaturated fatty acids containing 18 carbon atoms include:

FATTY ACIDS (continued) Cis carbon-carbon double bonds causes “kinking”of the carbon chain.

FATTY ACIDS (continued) Fatty acids with C=C bonds cannot pack closely together because of shape. This leads to Fatty acid melting points Most unsaturated fatty acids are at room temperature.

FATTY ACIDS (continued) are those needed by the body, but not synthesized within the body in adequate amounts. For humans, linoleic and linolenic acid are essential, but easily obtainable from plant and fish oils.

FATTY ACIDS (continued) Linoleic (an omega-3 fatty acid) and linolenic (an omega-6 fatty acid) acids: are used to produce hormonelike substances that regulate a wide range of functions and characteristics, including: e.g. blood pressure, blood clotting, blood lipid levels, the immune response, and the inflammation response to injury and infection. can be converted to other omega-3 and omega-6 fatty acids.