Announcements & Agenda (04/13/07)

1. Announcements& Agenda(04/13/07) • Extra Credit Assignment Due Monday • Quiz Today • Exam Fri 04/20 (Ch 13,14,15) • Today • Polysaccaharides • Lipids (15.1-15.3)

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

3. Last Time: Disaccharides to Know • A disaccharideconsists of two monosaccharides. Monosaccharides Disaccharide glucose + glucose maltose + H2O glucose + galactose lactose + H2O glucose + fructose sucrose + H2O • Factors that distinguish one disaccharide from another • Identity of monosaccharides • Type of glycosidic bond (e.g. maltose: a-1, 4 glycosidic bond) • Can still have a/b forms

4. Example: Sucrose • consists of α-D-glucose and β-D-fructose. • has an α,β-1,2-glycosidic bond. α-D-glucose β-D-fructose Is a non-reducing sugar. Why? http://en.wikipedia.org/wiki/Image:Glucose_Conversion.gif

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. • include amylose & amylopectin, starches 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. α-D-Glucose

8. Starch: Structures of Amylose & Amylopectin

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

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

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

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

13. 0 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. • are compared to sucrose (table sugar), which is assigned a value of 100. 60 000

16. History of Artificial Sweeteners • Saccharin: http://en.wikipedia.org/wiki/Saccharin • 1879 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. 1985 Monsanto bought GD Searle and created the NutraSweet Company. • Neotame (an analog of Aspartame) is 5 times sweeter than Aspartame. See http://www.neotame.com/

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

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

19. Types of Lipids: 2 Broad Classes

20. Fatty Acids • long-chain carboxylic acids. • typically 12-18 carbon atoms. • insoluble in water. • 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. • unsaturated:with one or more double C=C bonds.

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

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

26. 15.3 Waxes, Fats, and Oils

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

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

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

30. Formation of a Triacylglycerol glycerol + three fatty acids triacylglycerol + + 3H2O

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 prevalent in meats, whole milk, butter, and cheese. (mmm… cheese) An oil • is liquid at room temperature. • is prevalent in plants such as olive and safflower.

33. Oils w/ Unsaturated Fatty Acids • have more unsaturated fats. • 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. • have lower melting points than saturated fatty acids. • 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