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AnnouncementsAnnouncements & Agenda& Agenda (04/13/07)(04/13/07)

Extra Credit Assignment Due MondayExtra Credit Assignment Due MondayQuiz TodayQuiz TodayExam Fri 04/20 (Ch 13,14,15)Exam Fri 04/20 (Ch 13,14,15)

TodayToday PolysaccaharidesPolysaccaharides Lipids (15.1-15.3)Lipids (15.1-15.3)

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Last Time: Oxidation & Reduction Last Time: Oxidation & Reduction of Mono (and Di) Saccharidesof Mono (and Di) Saccharides

H

O

CH2OH

H OH

H OH

HO H

HHO

C OH

O

CH2OH

H OH

H OH

HO H

HHO

C

CH2OH

H OH

H OH

HO H

HHO

CH2OH

Reduction Oxidation

D-mannitol D-mannose D-mannonic acid

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Last Time: Disaccharides to KnowLast Time: Disaccharides to Know

• A A disaccharidedisaccharide consists of two monosaccharides. consists of two monosaccharides. Monosaccharides DisaccharideMonosaccharides Disaccharide

glucose + glucose glucose + glucose maltosemaltose + H + H22OO

glucose + galactoseglucose + galactose lactoselactose + H + H22OO

glucose + fructoseglucose + fructose sucrosesucrose + H + H22OO

• Factors that distinguish one disaccharide from anotherFactors that distinguish one disaccharide from another• Identity of monosaccharidesIdentity of monosaccharides• Type of glycosidic bond (e.g. maltose: Type of glycosidic bond (e.g. maltose: -1, 4 glycosidic -1, 4 glycosidic

bond)bond)• Can still have Can still have // forms forms

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Example: SucroseExample: Sucrose• consists of consists of αα--D-D-glucose and glucose and ββ--DD--fructose.fructose.• has an has an αα,,ββ-1,2-glycosidic bond.-1,2-glycosidic bond.

α-D-glucose

β -D-fructose

Is a non-reducing sugar. Why?Is a non-reducing sugar. Why?

http://en.wikipedia.org/wiki/Image:Glucose_Conversion.gifhttp://en.wikipedia.org/wiki/Image:Glucose_Conversion.gif

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Learning CheckLearning CheckWrite the structures of the two monosaccharides Write the structures of the two monosaccharides that form when sucrose is hydrolyzed.that form when sucrose is hydrolyzed.

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SolutionSolution

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PolysaccharidesPolysaccharides• often polymers of D-glucose.often polymers of D-glucose.• include amylose & amylopectin, include amylose & amylopectin,

starchesstarches made of made of αα-D-glucose.-D-glucose.• include include glycogenglycogen (animal starch (animal starch

in muscle), which is made of in muscle), which is made of αα--D-glucose.D-glucose.

• include include cellulosecellulose (plants and (plants and wood), which is made of wood), which is made of ββ-D--D-glucose.glucose.

α-D-Glucose

O

CH2OH

OHOH

OH

OH

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Starch: Structures of Amylose & AmylopectinStarch: Structures of Amylose & Amylopectin

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AmyloseAmylose

• a polymer of a polymer of αα-D--D-glucose molecules.glucose molecules.

• linked by linked by --1,4 1,4 glycosidic bonds.glycosidic bonds.

• a continuous a continuous (unbranched) (unbranched) chain. chain.

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AmylopectinAmylopectin

• also a polymer of also a polymer of αα--D-glucose molecules.D-glucose molecules.

• is a branched-chain is a branched-chain polysaccharide.polysaccharide.

• has has α-α-1,4-glycosidic 1,4-glycosidic bonds between the bonds between the glucose units.glucose units.

• has has αα--1,6 bonds to 1,6 bonds to branches.branches.

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GlycogenGlycogen

• is the is the polysaccharide polysaccharide that stores that stores αα-D--D-glucose in muscle.glucose in muscle.

• is similar to is similar to amylopectin, but amylopectin, but is more highly is more highly branched.branched.

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CelluloseCellulose

• a polysaccharide of a polysaccharide of glucose units in glucose units in unbranched chains.unbranched chains.

• has has ββ--1,4-glycosidic 1,4-glycosidic bonds.bonds.

• cannot be digested by cannot be digested by humans because humans because humans cannot break humans cannot break down the down the ββ--1,4-1,4-glycosidic bonds of glycosidic bonds of cellulose.cellulose.

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

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

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More Interesting Info: More Interesting Info: Sweetness of SweetenersSweetness of Sweeteners

• Sugars differ in Sugars differ in sweetness. sweetness.

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

60 000

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History of Artificial SweetenersHistory of Artificial SweetenersSaccharin: Saccharin: http://en.wikipedia.org/wiki/Saccharinhttp://en.wikipedia.org/wiki/Saccharin1879 Ira Remsen and Constantin Fahlberg at JHU1879 Ira Remsen and Constantin Fahlberg at JHUMonsanto Chemical Company in Saint Louis became Monsanto Chemical Company in Saint Louis became profitable in manufacturing and selling saccharin.profitable in manufacturing and selling saccharin.Aspartame (Nutrasweet) was originally patented by Aspartame (Nutrasweet) was originally patented by GD Searle in Chicago. 1985 Monsanto bought GD GD Searle in Chicago. 1985 Monsanto bought GD Searle and created the NutraSweet Company.Searle and created the NutraSweet Company.Neotame (an analog of Aspartame) is 5 times Neotame (an analog of Aspartame) is 5 times sweeter than Aspartame. See sweeter than Aspartame. See http://www.neotame.com/http://www.neotame.com/

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Chapter 15: Lipids… mmm…Fat…Chapter 15: Lipids… mmm…Fat…

15.1 Lipids15.1 Lipids15.2 Fatty Acids 15.2 Fatty Acids

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LipidsLipids

• biomolecules that contain fatty acids or a steroid biomolecules that contain fatty acids or a steroid nucleus.nucleus.

• soluble in organic solvents, but not in water.soluble in organic solvents, but not in water.• named for the Greek word named for the Greek word liposlipos, which means , which means

“fat.”“fat.”• extracted from cells using organic solventsextracted from cells using organic solvents..

Building blocks

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Types of Lipids: 2 Broad ClassesTypes of Lipids: 2 Broad Classes

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Fatty AcidsFatty Acids

• long-chain carboxylic long-chain carboxylic acids.acids.

• typically 12-18 carbon typically 12-18 carbon atoms.atoms.

• insoluble in water.insoluble in water.• saturated or saturated or

unsaturated.unsaturated.Olive oil contains 84% unsaturated fatty acids and 16% saturated fatty acids

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Saturated & Unsaturated Fatty AcidsSaturated & Unsaturated Fatty Acids

• saturated:saturated: all all single Csingle C–C –C bonds.bonds.

• unsaturated:unsaturated: with one or with one or more double more double C=C bonds.C=C bonds.

palmitic acid, a saturated acid

palmitoleic acid, an unsaturated acid

O

C OH

O

C OH

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Properties of Saturated Fatty AcidsProperties of Saturated Fatty Acids

• contain only single Ccontain only single C–C bonds.–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.

COOHCOOHCOOH

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Properties of Unsaturated Fatty AcidsProperties of Unsaturated Fatty Acids

• contain one or more contain one or more ciscis double C=double C=C bonds.C bonds.

• have “kinks” in the fatty have “kinks” in the fatty acid chains.acid chains.

• do not pack closely. do not pack closely. • have few attractions between have few attractions between

chains.chains.• have low melting points.have low melting points.• are liquids at room are liquids at room

temperature.temperature.

COOHH

H CC

HOOC

H

H

C

C

“kinks” in chain

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Learning Check Learning Check

Assign the melting points of –17°C, 13°C, and 69°C Assign the melting points of –17°C, 13°C, and 69°C to the correct fatty acid. Explain.to the correct fatty acid. Explain.

stearic acid stearic acid (18 C) (18 C) saturatedsaturatedoleic acid oleic acid (18 C) (18 C) one double one double

bondbondlinoleic acidlinoleic acid (18 C) (18 C) two double two double

bondsbonds

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Solution Solution

Stearic acid is saturated and would have a higher Stearic acid is saturated and would have a higher melting point than the unsaturated fatty acids. melting point than the unsaturated fatty acids. Because linoleic has two double bonds, it would have Because linoleic has two double bonds, it would have a lower mp than oleic acid, which has one double a lower mp than oleic acid, which has one double bond.bond.

stearic acid stearic acid mp 69°C mp 69°C saturatedsaturatedoleic acid oleic acid mp 13°Cmp 13°C

linoleic acid linoleic acid mp -17°C mp -17°C most unsaturatedmost unsaturated

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15.315.3Waxes, Fats, and Oils Waxes, Fats, and Oils

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WaxesWaxes• esters of saturated fatty acids and long-esters of saturated fatty acids and long-

chain alcohols.chain alcohols.• coatings that prevent loss of water by coatings that prevent loss of water by

leaves of plants. leaves of plants.

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Fats and Oils: TriacylglycerolsFats 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 Formed when the hydroxyl

groups of glycerol react with groups of glycerol react with the carboxyl groups of fatty the carboxyl groups of fatty acids.acids.

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In a In a triacylglyceroltriacylglycerol, glycerol forms ester , glycerol forms ester bonds with three fatty acidsbonds with three fatty acids. .

TriacylglycerolsTriacylglycerols

REMEMBER ACID CATALYZED ESTERIFICATION! …OR FROM LAB!

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OHCH2

OH

OHCH2

CHO

(CH2)14CH3CHO

O

(CH2)14CH3CHO

O

(CH2)14CH3CHO

Formation of a TriacylglycerolFormation of a Triacylglycerolglycerol + three fatty acids triacylglycerolglycerol + three fatty acids triacylglycerol

+ 3H+ 3H22OO

O

O

C (CH2)14CH3

CH O

O

C (CH2)14CH3

CH2 O

O

C (CH2)14CH3

CH2

+

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(CH2)12CH3

O

C

CH(CH2)7CH3(CH2)7CH

O

C

O

(CH2)16CH3C

O

O

OCH2

CH2

CH

Different Fatty Acids Can Make Different Fatty Acids Can Make Up Triacylglycerols!Up Triacylglycerols!

Stearic acid

Oleic acid

Myristic acid

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Melting Points of Fats and OilsMelting Points of Fats and Oils

A A fatfat • is solid at room temperature.is solid at room temperature.• is prevalent in meats, whole milk, butter, is prevalent in meats, whole milk, butter,

and cheese. (mmm… cheese)and cheese. (mmm… cheese)An An oiloil• is liquid at room temperature.is liquid at room temperature.• is prevalent in plants such as olive and is prevalent in plants such as olive and

safflower.safflower.

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Oils w/ Unsaturated Fatty AcidsOils w/ Unsaturated Fatty Acids• have more unsaturated fats.have more unsaturated fats.• have have cis cis double bonds that cause “kinks” double bonds that cause “kinks”

in the fatty acid chains.in the fatty acid chains.• with “kinks” in the chains do not allow the with “kinks” in the chains do not allow the

triacylglycerol molecules to pack closely.triacylglycerol molecules to pack closely.• have lower melting points than saturated have lower melting points than saturated

fatty acids.fatty acids.• are liquids at room temperature.are liquids at room temperature.

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Diagram of Triacylglycerol with Diagram of Triacylglycerol with Unsaturated Fatty AcidsUnsaturated Fatty Acids

Unsaturated fatty acid chains with kinks cannot pack closely.

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Percent Saturated and Unsaturated Fatty Percent Saturated and Unsaturated Fatty Acids In Fats and OilsAcids In Fats and Oils