1 announcements & agenda (04/09/07) extra credit assignment due now! pick up graded quizzes quiz...
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AnnouncementsAnnouncements & Agenda& Agenda (04/09/07)(04/09/07)
Extra Credit Assignment Due NOW!Extra Credit Assignment Due NOW!
Pick Up Graded QuizzesPick Up Graded Quizzes
Quiz Friday (13.4, 13.5, & Ch 14)Quiz Friday (13.4, 13.5, & Ch 14)
TodayToday More on Carbohydrates (14.1-14.3)More on Carbohydrates (14.1-14.3)
MonosaccharidesMonosaccharides
Cyclic MonosaccharidesCyclic Monosaccharides Reactions of carbohydratesReactions of carbohydrates DisaccharidesDisaccharides
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acid hydrolysisacid hydrolysis OO
|||| OO CH CH33——CC——OH + NHOH + NH44
++ClCl––
|||| HClHCl + H+ H22O O CHCH33——CC—NH—NH22
NaOHNaOH OO ||||
CHCH33——CC——OO– – NaNa++ + NH + NH33
base hydrolysisbase hydrolysis
Last Time: AmiLast Time: Amidde e HydrolysisHydrolysis
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Last Time: Carbohydrates IntroLast Time: Carbohydrates Intro
• a major source of a major source of energy from our diet energy from our diet
• composed of C, H, & Ocomposed of C, H, & O
• also known as also known as saccharides, which saccharides, which means “sugars.”means “sugars.”
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Last Time: Types of CarbohydratesLast Time: Types of Carbohydrates
• Monosaccharides:Monosaccharides: simplest carbohydrates. simplest carbohydrates. • Disaccharides:Disaccharides: consist of two monosaccharides. consist of two monosaccharides.• Polysaccharides:Polysaccharides: contain many monosaccharides. contain many monosaccharides.
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Last Time: MonosaccharidesLast Time: Monosaccharides
• typically 3-6 carbon atomstypically 3-6 carbon atoms
• have a C=O group (aldehyde or ketone)have a C=O group (aldehyde or ketone)• aldosesaldoses• ketosesketoses
• several hydroxyl groupsseveral hydroxyl groups
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AldosesAldoses
• monosaccharides with an monosaccharides with an aldehyde group… aldehyde group…
• ……and many hydroxyl and many hydroxyl groups.groups.
triose triose (3C atoms)(3C atoms)
tetrose tetrose (4C atoms)(4C atoms)
pentosepentose (5C atoms) (5C atoms)
hexose hexose (6C atoms)(6C atoms)
OO ║║
CC─H aldose─H aldose ││ HH── C C─OH─OH │ │ HH── C C─OH─OH │ │
CHCH22OHOH
ErythoseErythose
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KetosesKetoses
• monosaccharides with a monosaccharides with a ketone group…ketone group…
• ……and many hydroxyl and many hydroxyl groups.groups.
CCHH22OH OH
│ │ C=C=O ketoseO ketose │ │ HH── C C─OH─OH ││ HH── C C─OH─OH │ │
HH──CC─OH─OH ││
CHCH22OHOH
Fructose, a ketohexose
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Fischer ProjectionsFischer Projections
• also used to represent carbohydrates.also used to represent carbohydrates.• places the most oxidized group at the top.places the most oxidized group at the top.• shows chiral carbons as the intersection of shows chiral carbons as the intersection of
vertical and horizontal lines.vertical and horizontal lines.
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D & L Notations: Know This Now…D & L Notations: Know This Now…In a Fischer projection, the In a Fischer projection, the −OH group on the−OH group on the• chiral carbon chiral carbon farthest from the carbonyl groupfarthest from the carbonyl group
determines an L or D isomer. determines an L or D isomer. • left = left = LL for the L-formfor the L-form..• right = right = DD for the D-formfor the D-form. (MOST COMMON IN . (MOST COMMON IN
NATURE!)NATURE!)
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Learning CheckLearning Check
Identify each as the D or L isomer.Identify each as the D or L isomer.
A.A. B.B. C. C.
__-Ribose __-Ribose __- Threose __- Fructose __- Threose __- Fructose
CH2OH
HO H
HO H
HHO
O
C H
CH2OH
HO H
OHH
O
C H
CH2OH
H OH
H OH
HO H
O
CH2OH
L L D
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D-GlucoseD-Glucose
• found in fruits, corn found in fruits, corn syrup, and honeysyrup, and honey
• an an aldoaldohexose with hexose with the formula Cthe formula C66HH1212OO66
• known as known as blood blood sugarsugar in the body in the body
• the monosaccharide the monosaccharide in polymers of in polymers of starch, cellulose, starch, cellulose, and glycogenand glycogen
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Blood Glucose LevelBlood Glucose LevelIn the body, In the body, • normal blood: [glucose] = 70-90 mg/dL.normal blood: [glucose] = 70-90 mg/dL.• a glucose tolerance test measures blood a glucose tolerance test measures blood
glucose for several hours after ingesting glucose for several hours after ingesting glucose.glucose.
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D-FructoseD-Fructose
• is a is a ketoketohexose hexose CC66HH1212OO66
• is the is the sweetest sweetest carbohydratecarbohydrate
• found in fruit juices found in fruit juices and honeyand honey
• converts to converts to glucose in the glucose in the bodybody
H OH
CH2OH
C
HO
H OH
H
C
O
C
C
CH2OH
D-Fructose
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D-GalactoseD-Galactose
• is an is an aldoaldohexose hexose CC66HH1212OO66..
• notnot found free in nature. found free in nature.• is obtained from lactose, is obtained from lactose,
a disaccharide.a disaccharide.• has a similar structure to has a similar structure to
glucose except for the glucose except for the
– –OH on C4OH on C4
Which C is C4???Which C is C4???
H
H
H OH
CH2OH
C
HO
HO HC
OH
C
C
O
C H
D-Galactose
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Cyclic Structures (14.3)Cyclic Structures (14.3)
• prevalent form of monosaccharides with 5 or 6 prevalent form of monosaccharides with 5 or 6 carbon atomscarbon atoms
• form when the hydroxyl group on C-5 reacts form when the hydroxyl group on C-5 reacts with the aldehyde group or ketone groupwith the aldehyde group or ketone group• Orgo-Chem reaction not previously mentioned: Orgo-Chem reaction not previously mentioned:
“C=O” + ROH “C=O” + ROH → hemiacetal→ hemiacetal
O O
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Drawing Cyclic Structures: Practice! Drawing Cyclic Structures: Practice! Example: GlucoseExample: Glucose
STEP 1STEP 1 Number the carbon chain and turn Number the carbon chain and turn clockwise to form a linear open chain. clockwise to form a linear open chain.
HHO
H
CH2OH
OHC
H
H
OH
OH
C
C
C
OH
C1
2
3
4
5
6
6 5 4 3 2 1
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OH
OH
OHOH
CH2OH
O
Cyclic Structure for GlucoseCyclic Structure for GlucoseSTEP 2STEP 2 Fold into a hexagon. Fold into a hexagon. • Bond the C5 –O– to C1. Bond the C5 –O– to C1. • Place the C6 group above the Place the C6 group above the
ring. ring. • Write the –OH groups on C2 Write the –OH groups on C2
& C4 below the ring (These & C4 below the ring (These are the C atoms that pointed are the C atoms that pointed down from Step 1). down from Step 1).
• Write the –OH group on C3 Write the –OH group on C3 above the ring. above the ring.
• Write a new –OH on C1.Write a new –OH on C1.
6 5
4 1
3 2
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Cyclic Structure for GlucoseCyclic Structure for Glucose
OH
OH
OHOH
CH2OH
O
-D-Glucose -D-Glucose
OH
OH
OHOH
CH2OH
O
STEP 3 Write the new –OH on C1 • down for the form.• up for the form.
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MutarotationMutarotation
• 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
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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
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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.
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+ 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…
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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
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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
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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
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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
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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
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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
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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.