1 Announcements & Agenda (04/13/07) Extra Credit Assignment Due Monday Quiz Today Exam Fri 04/20 (Ch 13,14,15) Today Polysaccaharides Polysaccaharides Lipids ( ) Lipids ( )

2 Last Time: Oxidation & Reduction of Mono (and Di) Saccharides D-mannitol D-mannose D-mannonic acid

3 Last Time: Disaccharides to Know A disaccharide consists of two monosaccharides.A disaccharide consists of two monosaccharides. Monosaccharides Disaccharide glucose + glucose maltose + H 2 O glucose + glucose maltose + H 2 O glucose + galactoselactose + H 2 O glucose + fructosesucrose + H 2 O Factors that distinguish one disaccharide from anotherFactors that distinguish one disaccharide from another Identity of monosaccharides Identity of monosaccharides Type of glycosidic bond (e.g. maltose:  -1, 4 glycosidic bond) Type of glycosidic bond (e.g. maltose:  -1, 4 glycosidic bond) Can still have  /  forms Can still have  /  forms

4 Example: Sucrose consists of α-D-glucose and β-D-fructose.consists of α-D-glucose and β-D-fructose. has an α,β-1,2-glycosidic bond.has an α,β-1,2-glycosidic bond. α-D-glucose β -D-fructose Is a non-reducing sugar. Why?

5 Learning Check Write the structures of the two monosaccharides that form when sucrose is hydrolyzed.

6 Solution

7 Polysaccharides often polymers of D-glucose.often polymers of D-glucose. include amylose & amylopectin, starches made of α-D-glucose.include amylose & amylopectin, starches made of α-D-glucose. include glycogen (animal starch in muscle), which is made of α- D-glucose.include glycogen (animal starch in muscle), which is made of α- D-glucose. include cellulose (plants and wood), which is made of β-D- glucose.include cellulose (plants and wood), which is made of β-D- glucose. α-D-Glucose

8 Starch: Structures of Amylose & Amylopectin

9 Amylose a polymer of α-D- glucose molecules.a polymer of α-D- glucose molecules. linked by  -1,4 glycosidic bonds.linked by  -1,4 glycosidic bonds. a continuous (unbranched) chain.a continuous (unbranched) chain.

10 Amylopectin also a polymer of α-D-glucose molecules.also a polymer of α-D-glucose molecules. is a branched-chain polysaccharide.is a branched-chain polysaccharide. has α-1,4- glycosidic bonds between the glucose units.has α-1,4- glycosidic bonds between the glucose units. has α-1,6 bonds to branches.has α-1,6 bonds to branches.

11 Glycogen is the polysaccharide that stores α-D- glucose in muscle.is the polysaccharide that stores α-D- glucose in muscle. is similar to amylopectin, but is more highly branched.is similar to amylopectin, but is more highly branched.

12 Cellulose a polysaccharide of glucose units in unbranched chains.a polysaccharide of glucose units in unbranched chains. has β-1,4-glycosidic bonds.has β-1,4-glycosidic bonds. cannot be digested by humans because humans cannot break down the β- 1,4-glycosidic bonds of cellulose.cannot be digested by humans because humans cannot break down the β- 1,4-glycosidic bonds of cellulose.

13 Other cool sugars… Chitin (glucose w/ amide) = insect exoskeleton. Similar to that in bacterial cell wall; makes bacterial cells hard to break open. Lysozyme – defense protein to break down cell walls Cell surface, including ABO blood groups.

14 You are responsible for the Health Note on Page 485!

15 More Interesting Info: Sweetness of Sweeteners Sugars differ in sweetness.Sugars differ in sweetness. are compared to sucrose (table sugar), which is assigned a value of 100.are compared to sucrose (table sugar), which is assigned a value of

16 History of Artificial Sweeteners Saccharin: Ira Remsen and Constantin Fahlberg at JHU Monsanto Chemical Company in Saint Louis became profitable in manufacturing and selling saccharin. Aspartame (Nutrasweet) was originally patented by GD Searle in Chicago Monsanto bought GD Searle and created the NutraSweet Company. Neotame (an analog of Aspartame) is 5 times sweeter than Aspartame. See

17 Chapter 15: Lipids… mmm…Fat… 15.1 Lipids 15.2 Fatty Acids

18 Lipids biomolecules that contain fatty acids or a steroid nucleus.biomolecules that contain fatty acids or a steroid nucleus. soluble in organic solvents, but not in water.soluble in organic solvents, but not in water. named for the Greek word lipos, which means “fat.”named for the Greek word lipos, which means “fat.” extracted from cells using organic solvents.extracted from cells using organic solvents. Building blocks

19 Types of Lipids: 2 Broad Classes

20 Fatty Acids long-chain carboxylic acids.long-chain carboxylic acids. typically carbon atoms.typically carbon atoms. insoluble in water.insoluble in water. saturated or unsaturated.saturated or unsaturated. Olive oil contains 84% unsaturated fatty acids and 16% saturated fatty acids

21 Saturated & Unsaturated Fatty Acids saturated: all single C–C bonds.saturated: all single C–C bonds. unsaturated: with one or more double C=C bonds.unsaturated: with one or more double C=C bonds.

22 Properties of Saturated Fatty Acids contain only single C–C bonds.contain only single C–C bonds. are closely packed.are closely packed. have strong attractions between chains.have strong attractions between chains. have high melting points.have high melting points. are solids at room temperature.are solids at room temperature.

23 Properties of Unsaturated Fatty Acids contain one or more cis double C=C bonds.contain one or more cis double C=C bonds. have “kinks” in the fatty acid chains.have “kinks” in the fatty acid chains. do not pack closely. do not pack closely. have few attractions between chains. have few attractions between chains. have low melting points. have low melting points. are liquids at room temperature. are liquids at room temperature. “kinks” in chain

24 Learning Check Assign the melting points of –17°C, 13°C, and 69°C to the correct fatty acid. Explain. stearic acid (18 C) saturated oleic acid (18 C) one double bond linoleic acid(18 C) two double bonds

25 Solution Stearic acid is saturated and would have a higher melting point than the unsaturated fatty acids. Because linoleic has two double bonds, it would have a lower mp than oleic acid, which has one double bond. stearic acid mp 69°C saturated oleic acid mp 13°C linoleic acid mp -17°C most unsaturated

Waxes, Fats, and Oils

27 Waxes esters of saturated fatty acids and long- chain alcohols.esters of saturated fatty acids and long- chain alcohols. coatings that prevent loss of water by leaves of plants.coatings that prevent loss of water by leaves of plants.

28 Fats and Oils: Triacylglycerols also called triacylglycerols.also called triacylglycerols. esters of glycerol.esters of glycerol. produced by esterification.produced by esterification. Formed when the hydroxyl groups of glycerol react with the carboxyl groups of fatty acids.Formed when the hydroxyl groups of glycerol react with the carboxyl groups of fatty acids.

29 In a triacylglycerol, glycerol forms ester bonds with three fatty acids. Triacylglycerols REMEMBER ACID CATALYZED ESTERIFICATION! …OR FROM LAB!

30 Formation of a Triacylglycerol glycerol + three fatty acids triacylglycerol + 3H 2 O +

31 Different Fatty Acids Can Make Up Triacylglycerols! Stearic acid Oleic acid Myristic acid

32 Melting Points of Fats and Oils A fat is solid at room temperature.is solid at room temperature. is prevalent in meats, whole milk, butter, and cheese. (mmm… cheese)is prevalent in meats, whole milk, butter, and cheese. (mmm… cheese) An oil is liquid at room temperature.is liquid at room temperature. is prevalent in plants such as olive and safflower.is prevalent in plants such as olive and safflower.

33 Oils w/ Unsaturated Fatty Acids have more unsaturated fats.have more unsaturated fats. have cis double bonds that cause “kinks” in the fatty acid chains.have cis double bonds that cause “kinks” in the fatty acid chains. with “kinks” in the chains do not allow the triacylglycerol molecules to pack closely.with “kinks” in the chains do not allow the triacylglycerol molecules to pack closely. have lower melting points than saturated fatty acids.have lower melting points than saturated fatty acids. are liquids at room temperature.are liquids at room temperature.

34 Diagram of Triacylglycerol with Unsaturated Fatty Acids Unsaturated fatty acid chains with kinks cannot pack closely.

35 Percent Saturated and Unsaturated Fatty Acids In Fats and Oils