CARBOHYDRAT E CHEMISTRY

Dr.Almoeiz Yousif MS.c.,Ph.D.,MEE

Carbohydrates • (hydrates of carbon) • Carbo(C)……Hydrate Most have formula general Carbo(C)……Hydrate (CH 2 O ) n or H

-

C

I I

-

OH C n H 2 n O n

2 Thursday, April 23, 2020

Carbohydrate Definition

2020 , , polyhydroxyaldehyde or 23 polyhydroxyketone, or a substance that can be hydrolyzed to form these April Thursday, compounds

I (CH2O)n or H - C - OH I 3 Functions of • •

Energysource Structural role

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Classification of Carbohydrates

2020

Monosaccharides - simple , 23

- 2 April Thursday, covalently linked.

Oligosaccharides – 3 to 10 monosaccharides covalently linked.

Polysaccharides - more than 5 10 units covalently linked.

Monosaccharides A monosaccharide is acarbohydrate • (simplesugar) that cannot be hydrolyzed toa simpler also blood sugar blood also • • • biologically importantonesare: : most common sugar, sugar, common most :

: fruit sugar sugar fruit : : sugar found in milk milk in found sugar :

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Properties of Monosaccharides

2020 , , • Simplest of carbohydrates 23

• Sweet-tasting Thursday, April April Thursday, • Dissolve in water • Straight chain or ring structure • Reducing sugars

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Monosaccharide Classification

2020 , ,

• 1- On the basis of the numbers of 23 carbon atoms

• 2- On the basis of the functional April Thursday, group.

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1. According to number of carbons

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23 • 3 carbons • 4 • 5 () April Thursday, • 6 (glucose,fructose galactose) • 7 • 8 • 9

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2.According to functional group

2020 , ,

Aldoses have an aldehyde have a keto group, 23 group at one end. usually at C2.

H O April Thursday, C CH2OH

H C OH C O

HO C H HO C H

H C OH H C OH

H C OH H C OH CH OH CH2OH 2 10 D-glucose D-fructose ISOMERS: same chemical

formulae

2020

, , 23

C6H12O6 Thursday, April April Thursday,

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ISOMERS OF MONOSACCHARIDES

2020 , ,

1) D- and L- isomers 23

Thursday, April April Thursday, = mirror images (enantiomers)

nature important: D-monosaccharides

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2) and Ketoses

2020

, , 23

H O April Thursday, C CH2OH

H C OH C O

HO C H HO C H

H C OH H C OH

H C OH H C OH CH OH CH2OH 2 13 D-glucose D-fructose

2020 , ,

23 Thursday, April April Thursday,

14 3) and

Sugars Prefer To Be Cyclic in solutions

2020

, ,

23 Thursday, April April Thursday,

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2020

, , 23

April Thursday, 99% of Glucose in solution is found in form

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4)  and 

2020 , ,

23 only cyclic molecules

April Thursday,

-D-Glc

17 * OH orientation of anomeric carbon is the basis of this

classification. 2020 β : Same side with the side chain( the last , carbon atom) 23 α anomer : opposite side with the side chain

April Thursday,

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5) epimers

2020 , , EPIMERS:differ in 23 conformation around

ONE carbon April Thursday,

Man = 2-epimer of Glc Gal = 4-epimer of Glc

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2020

, ,

23 Thursday, April April Thursday,

Gal is found in Galaltose and are (milk sugar) epimers of glucose

20 Joining of

monosaccharaides

2020

, 23 • Monosaccharaides can be joined to form

disaccharides, , and Thursday, April April Thursday,

. Important disaccharides include

lactose (galactose + glucose), (glucose +

fructose), and (glucose + glucose).

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2020

, , 23 • Important polysaccharides include branched

(from animal sources) and (plant Thursday, April April Thursday,

sources) and unbranched (plant sources);

each is a polymer of glucose.

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Glycosidic bond

2020

, , 23 • a or glycosidic linkage is a type of

covalent bond that joins a carbohydrate (sugar) Thursday, April April Thursday,

molecule to another .

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Naming glycosidic bonds:

2020

, , 23 • Glycosidic bonds between sugars are named

according to the numbers of the connected Thursday, April April Thursday,

carbons, and also with regard to the position of the

anomeric hydroxyl group of the sugar involved in the

bond. If this anomeric hydroxyl is in the α

configuration, the linkage is an α-bond. 24

2020

, , 23 • If it is in the β configuration, the linkage is a β-bond.

Lactose, for example, is synthesized by forming a Thursday, April April Thursday,

glycosidic bond between carbon 1 of β-galactose

and carbon 4 of glucose. The linkage is, therefore, a

β(1→4) glycosidic bond

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23 Thursday, April April Thursday,

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DISACCHARIDES

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23

• Sucrose Thursday, April April Thursday, • LActose • MaltosE

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2020 , , • Two joined monosaccharaides are called a disaccharide 23

and these are the simplest polysaccharides. Examples Thursday, April April Thursday, include sucrose and lactose. They are composed of two

monosaccharide units bound together by a covalent bond

known as a glycosidic linkage formed via a dehydration

reaction, resulting in the loss of a hydrogen atom from

one monosaccharide and a hydroxyl group from the other. 30

Lactose Sucrose Maltose • Two Two simplesugars together.joined linkage

monosaccharaides

(milk (milk sugar) = glucose + galactose

(table sugar) = glucose + fructose (malt (malt sugar) = glucose + glucose

to form a Disaccharides disaccharide can join with a .

glycosidic

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Maltose

2020 , ,

23 • Maltose is formed by joining two

glucose molecules. April Thursday,

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Sucrose

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, , 23

• is formed by joining glucose and fructose. Thursday, April April Thursday,

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Lactose

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, ,

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Lactose Intolerance

2020 , , • Symptoms 23

• Bloating, abdominal discomfort, and April Thursday,

diarrhea

• Causes

• Lactase deficiency 36

Oligosaccharid es

• Oligosaccharides e.g.

• • 3 - 10

monosaccharaides linked togetherlinked monosaccharaides

( 6 -

8 ( 3 glucose units glucose units

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Polysaccharides

Polysaccharides

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, , 23 • Polysaccharides: more than 10 monosaccharide

units linked together. Thursday, April April Thursday,

• polysaccharides are insoluble in water.

• Polysaccharides can be polymers of hexose or

pentose sugars.

40 : Glycogen: Cellulose: Starch: • animals. plants. Examples exoskeletons of insects. of exoskeletons

Polysaccharides

Structural elementthe in Storage form of glucose of glucose Storage formin

Structural element ofplants. Structural

: Polymers of glucose of Polymers : Storage form of glucose in of form Storage

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GLYCOGEN

GLUCOSE IS STORED AS GLYCOGEN IN

2020 , ,

LARGE AMOUNTS IN BOTH THE LIVER AND 23

SKELETAL MUSCLES Thursday, April April Thursday,

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Structural Polysaccharides

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• Chitin is the major 23 element in the exoskeleton of insects

and crustacea where it April Thursday, affords protection and support.

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