11

AnnouncementsAnnouncements & Agenda& Agenda (04/11/07)(04/11/07)

New Extra Credit Assignment Due MondayNew Extra Credit Assignment Due MondayPick Up Old Graded StuffPick Up Old Graded StuffPick Up Flowchart if you were absent MondayPick Up Flowchart if you were absent MondayQuiz Friday (13.4, 13.5, & Ch 14)Quiz Friday (13.4, 13.5, & Ch 14)Exam Fri 04/20 (Ch 13,14,15)Exam Fri 04/20 (Ch 13,14,15) Will Post Practice Exam Soon!Will Post Practice Exam Soon!

TodayToday Finish Cyclic MonosaccharidesFinish Cyclic Monosaccharides Reactions of carbohydratesReactions of carbohydrates DisaccharidesDisaccharides PolysaccaharidesPolysaccaharides

22

What sugar is this?What sugar is this?

0%

0%

0%

0% 1.1. MannoseMannose

2.2. GlucoseGlucose

3.3. FructoseFructose

4.4. GalactoseGalactose

11 22 33 44 55

33

Is this the L- form or the D-form?Is this the L- form or the D-form?

0%

0%

0% 1.1. LL

2.2. DD

3.3. BB

11 22 33 44 55

44

Which Structure is Correct?Which Structure is Correct?

0%

0%

0%

0% 1.1. AA

2.2. BB

3.3. CC

4.4. DD

11 22 33 44 55

55

Last Time: Formation of Cyclic GlucoseLast Time: Formation of Cyclic Glucose

Two “anomers” possible: Two “anomers” possible: and and ; this one is alpha ; this one is alpha b/c the –OH is opposite the -CHb/c the –OH is opposite the -CH22OH group!OH group!

66

Mutarotation: Interconversion of AnomersMutarotation: Interconversion of Anomers

• cyclic structures open and close. cyclic structures open and close. -D-glucose converts to -D-glucose converts to ββ-D-glucose & vice versa.-D-glucose & vice versa.• at any time, only aat any time, only a small amount of open chain forms. small amount of open chain forms.

-D-glucose D-glucose (open) -D-glucose D-glucose (open) ββ-D-glucose-D-glucose

(36%) (trace)(36%) (trace) (64%) (64%)

OH

CH2OH

OH

OC

H

OH

OHOH

OH

OHOH

CH2OH

OOH

OH

OHOH

CH2OH

O

77

D-fructoseD-fructose -D-fructose-D-fructoseαα-D-fructose-D-fructose

O CH2OH

OOHH

OH

OH

CH2OH

O OOHH

CH2OH

OH

OH

CH2OH

H OH

H OH

HHO

O

CH2OH

C

C

C

C

CH2OH

Cyclic Structure of FructoseCyclic Structure of Fructose

• is a ketohexose.is a ketohexose.• reacts the reacts the --OH on C-5 with the C=O on C-2OH on C-5 with the C=O on C-2

-OH from C5 attaches to C from C=O!-OH from C5 attaches to C from C=O!

88

Chemical Properties of Chemical Properties of Monosaccharides (14.4)Monosaccharides (14.4)

99

Reducing SugarsReducing Sugars

• are monosaccharides that oxidize to give are monosaccharides that oxidize to give a carboxylic acid. a carboxylic acid.

• undergo reaction in the Benedict’s test. undergo reaction in the Benedict’s test.

• include the monosaccharides glucose, include the monosaccharides glucose, galactose, and fructose.galactose, and fructose.

• many disaccharides can also oxidizemany disaccharides can also oxidize• but only if one monosaccharide can ring but only if one monosaccharide can ring

open! (see later slides)open! (see later slides)

1010

+ Cu2O(s)

D-gluconic acidD-glucose

+ Cu2+

H OH

H OH

HHO

H OH

O

OH

CH2OH

C

C

C

C

C

H OH

H OH

HHO

H OH

O

H

CH2OH

C

C

C

C

C

Oxidation of D-GlucoseOxidation of D-Glucose

[O]

QUESTION:QUESTION: WHY CAN FRUCTOSE (A KETONE) BE OXIDIZED??? WHY CAN FRUCTOSE (A KETONE) BE OXIDIZED???

ANSWER:ANSWER: ISOMERIZATION TO AN ALDEHYDE… ISOMERIZATION TO AN ALDEHYDE…

1111

One Test for Glucose in Urine:One Test for Glucose in Urine:Benedict’s TestBenedict’s Test

1212

Reduction of MonosaccharidesReduction of Monosaccharides

• involves the involves the carbonyl group.carbonyl group.

• produces sugar produces sugar alcohols, or alcohols, or alditols.alditols.

• such as D-such as D-glucose gives D-glucose gives D-glucitol also called glucitol also called sorbitol.sorbitol.

D-Glucitol

1313

Learning CheckLearning Check

Write the products of the oxidation and Write the products of the oxidation and reduction of D-mannose.reduction of D-mannose.

H

O

CH2OH

H OH

H OH

HO H

HHO

C

D-mannose

1414

SolutionSolution

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

1515

Disaccharides (14.5)Disaccharides (14.5)

1616

Important Disaccharides: Know These 3Important Disaccharides: Know These 3

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

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MaltoseMaltose

Free α-OH

A.K.A. “malt sugar”A.K.A. “malt sugar”

obtained from starch obtained from starch hydrolysishydrolysis

used in cereals, used in cereals, candies, and brewingcandies, and brewing

linked by an linked by an -1,4--1,4-glycosidicglycosidic bondbond formed formed from the from the −OH on C1 −OH on C1 of the 1st glucose and of the 1st glucose and −OH on C4 of the 2nd −OH on C4 of the 2nd glucoseglucose

found in both the found in both the - - and and ββ - forms - forms

1818

LactoseLactose

• a disaccharide of a disaccharide of ββ--DD--galactose galactose and and αα- - oror ββ-D--D-glucose.glucose.

• contains a contains a ββ -1,4- -1,4-glycosidic bondglycosidic bond..

• is found in milk is found in milk and milk products.and milk products.

α-formα-form

1919

SucroseSucroseSucroseSucrose or or table sugartable sugar• is obtained from sugar cane and sugar beets.is obtained from sugar cane and sugar beets.• 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?

2020

Learning CheckLearning Check

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

2121

SolutionSolution

2222

PolysaccharidesPolysaccharides

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

starches made of starches made of αα-D-glucose.-D-glucose.• include glycogen (animal starch include glycogen (animal starch

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

• include cellulose (plants and include cellulose (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

2323

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

2424

AmyloseAmylose

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

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

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

2525

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.

2626

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.

2727

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

2828

Learning CheckLearning Check

Identify the polysaccharides and types Identify the polysaccharides and types of glycosidic bonds in each of the of glycosidic bonds in each of the following.following.

A.A. B.B. C.C.

2929

Solution Solution

A. Cellulose A. Cellulose --1,4-glycosidic bonds1,4-glycosidic bonds

B. Amylose B. Amylose --1,4-glycosidic bonds1,4-glycosidic bonds

Amylopectin Amylopectin --1,4-and 1,4-and --1,6-glycosidic bonds1,6-glycosidic bonds

C. GlycogenC. Glycogen --1,4-and 1,4-and --1,6-glycosidic bonds1,6-glycosidic bonds

(more branched than amylopectin)(more branched than amylopectin)

3030

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 walls

Cell surface, including ABO blood groups.Cell surface, including ABO blood groups.

3131

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

3333

History of Artificial SweetenersHistory of Artificial Sweeteners

Saccharin: Saccharin: http://en.wikipedia.org/wiki/Saccharinhttp://en.wikipedia.org/wiki/Saccharin

1879 Ira Remsen and Constantin Fahlberg at JHU1879 Ira Remsen and Constantin Fahlberg at JHU

Monsanto 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 sweeter Neotame (an analog of Aspartame) is 5 times sweeter than Aspartame. See http://www.neotame.com/than Aspartame. See http://www.neotame.com/

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

15.1 Lipids15.1 Lipids

15.2 Fatty Acids 15.2 Fatty Acids