Carbohydrates
Dr. Nasim
AP Biochem
Dr. Nasim
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Monosaccharides
(Single sugar residue)
3 C:
4 C:
5 C:
6 C:
6 C:
Trioses
Tetroses
Pentoses
Hexoses
Hexoses
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Monosaccharides
(Single sugar residue)
(Aldose)
(ketose)
 Glyceraldehydes
 Erythrose
 Ribose
 Xylose
 Glucose
DHA 3C
Erthrulose - 4 C
Ribulose - 5 C
Xylulose
5C
Fructose - 6 C
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Monosaccharides
Aldoses: Those Monosaccharides which
contain Aldehyde group. (H-C=O)
Ketose: Those Monosaccharides which
contain keto group. (C=O)
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Monosaccharides
Anomeric carbon: Aldoses & Ketose
may cyclize to produce an Anomeric
carbon.
Anomeric carbon contain reactive
hydroxyl group.
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Monosaccharides
If the Reactive hydroxyl group is free (Not
attached to any other molecule) then the
sugar is known as reducing sugars.
Reactive hydroxyl group may attached
covalently to another molecule.
N-Glycosidic linkage: If the Reactive
hydroxyl group is attached to–NH2
group.
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Monosaccharides
O-Glycosidic linkage: If the Reactive
hydroxyl group is attached to–OH group.
ISOMERS: If 2 compound have the same
chemical formula. E.g. Fructose &
glucose are isomers of each other.
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Monosaccharides
Epimers: If 2 compound have the same
chemical formula but the differ in
configuration around 1 specific C atom.
Galactose & glucose are C 4 Epimers of
each other.
Mannose & glucose are C 2 Epimers of
each other.
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Monosaccharides
Enantiomers: If 2 compound are mirror image
of each others.
 E.g. L - Glucose & D – Glucose.
 The configuration of asymmetric carbon atom
farthest from the aldehyde or keto group (with
reference to D or L glyceraldehydes)
determines whether a monosaccharide is of D
or L series.
 In D form OH gp is on right side & vice versa in
left side.
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Disaccharides
(2 Monosaccharides units)
Sucrose = Glucose + Fructose
(α1-2 linkage)
Lactose = Glucose + Galactose
(β1-4 linkage)
Maltose = Glucose + Glucose
(α1-4 linkage)
Iso-malotose = Glucose + Glucose (α1-6)
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Oligosaccharides
(3-10 Monosaccharides)
 E.g. Maltotriose: Compose of 3 Glucose
residues.
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Polysaccharides
(>10 Monosaccharides units)
Homo Polysaccharides
(contain same type of monosaccharides)
Glycogen which is also known as animal
starch.
Dextrin
Dextran
Cellulose
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Polysaccharides
Hetero Polysaccharides
(contain same type of monosaccharides
or different monosaccharides along with
prosthetic groups)
Muco Polysaccharides
Mucilages
Hemicellulose
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Polysaccharides
Hetero Polysaccharides
 Muco Polysaccharides
Hyaluronic acid
Heparin
Chondroitin sulphate
Blood group Polysaccharides.
Serum mucoids
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Polysaccharides
Hetero Polysaccharides
 Mucilages
Agar
Vegetable
Pectin
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Monosaccharides
Glyceraldehydes:
Reference sugar
All sugars are derived from it
D & L forms are refer to it
DHA
Produced from glucose in glycolysis &
also from glycerol which is produced in
break down of fats
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Monosaccharides
Erythrose & Erthrulose
Produced from glucose in HMP shunt
Can be converted to glucose
Ribose
Produced from glucose in HMP shunt
Ribose component of RNA
Deoxy-Ribose component of RNA
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Monosaccharides
Ribulose, Xylose & Xylulose
Produced from glucose in HMP shunt
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Monosaccharides
Glucose
Grape sugar
Dextrose
Dextro-rotation
Most common source sucrose which is
table sugar
Main source of energy for body &
specially brain.
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Monosaccharides
Glucose (Cont.)
FBS 60 – 100 mg/dl
RBS 100 – 160 mg/dl
On reduction glucose forms alcohol e.g.
Sorbitol
On oxidation sugar acids
Gluconic acid If oxidation of C1 of
glucose
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Monosaccharides
Glucose (Cont.)
Glucuronic acid If oxidation of C6 of
glucose
Glucaric acid If oxidation of C1& C6 of
glucose
Glucuronic acid is used for detoxification
of various toxic substances
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Monosaccharides
Galactose
Main source Lactose which is milk sugar
C 4 epimer of glucose
Mannose
Can be converted to glucose
On reduction forms Mannitol
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Monosaccharides
Fructose
 Levulose.
 Levo-rotation.
 Sweetest among all sugars.
 Most common source Sucrose (table sugar).
 Pure honey = Fructose only.
 Fructose  Glucose.
 Entry into cells is independent of Insulin.
 Source of energy for sperms.
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Disaccharides
Maltose = Glucose + Glucose (α1-4)
Fruit sugar
Reducing sugar
Produced from starch by hydrolysis due
to salivary & pancreatic amylase.
Hydrolyzed by Maltase
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Disaccharides
Lactose = Glucose+ Galactose (β1-4)
Milk sugar
Reducing sugar
Hydrolyzed by Lactase
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Disaccharides
Sucrose = Glucose + Fructose (α1-2)
Cane sugar
Table sugar
Non-reducing sugar
Invert sugar
Hydrolyzed by Sucrase (Invertase)
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Polysaccharides
Homo Polysaccharides
Glycogen
Store from of Glucose
Present mostly in Liver & Muscles.
Animal starch
Branched structure (Tree like)
Less then 12 glucose residues
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Polysaccharides
Homo Polysaccharides
Glycogen (Cont.1)
Within a chain (α1-4) broken by
Phosphorylase enzyme.
At branch point (α1-6) broken by debranching enzyme.
Blood glucose levels are usually
maintained by Liver glycogen stores.
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Polysaccharides
Homo Polysaccharides
Starch
Most of dietary carbohydrates are in this
form.
2 types
Amylose (Straight chain)
Amylopectin (Branched structure) more
then 12 residues in each chain.
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Polysaccharides
Homo Polysaccharides
Starch (Cont.)
Hydrolyzed by salivary & Pancreatic
amylase into Maltose, Maltotriose &
dextrins.
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Polysaccharides
Homo Polysaccharides
Dextrins
Intermediate product of hydrolysis of
starch.
E.g. Amylodextrins, Erythrodextrins &
Achrodextrins.
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Polysaccharides
Homo Polysaccharides
Dextrans
Highly viscous.
Polysaccharides
Plasma expander.
Cellulose
Can’t be digested.
Increase bulk of stool.
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Polysaccharides
Hetero Polysaccharides
Muco Polysaccharides
Animal origin
Mucoprotein & Mucin (when in
combination with proteins)
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Polysaccharides
Hetero Polysaccharides
Muco Polysaccharides
Subtypes
 Hyaluronic Acid
 Chondroitin sulphate
 Heparin
 Blood group Polysaccharides
 Serum mucoids
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Polysaccharides
Muco Polysaccharides
Hyaluronic Acid (Cementing agent)
 Present in skin, synovial fluid, seminal
fluid & vitreous humor.
 Functions
 Prevents penetration of bacteria into skin
 Lubrication of the joints
 Helps in fertilization
 Hydrolyzed by Hyaluronidase
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Polysaccharides
Muco Polysaccharides
 Chondroitin sulphate
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Polysaccharides
Muco Polysaccharides
 Heparin
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Polysaccharides
Muco Polysaccharides
 Blood group Polysaccharides
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Polysaccharides
Muco Polysaccharides
Serum mucoids
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Polysaccharides
Mucilages
Plant origin
Agar
Non-digestible
Laxative
Culture media
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Polysaccharides
Vegetable gums
Used in pharmaceutical industry
Pectins
For making jellies
Hemicellulose
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Asymmetric carbon atom
 Asymmetric carbon atom: The carbon atom to
which 4 different chemical groups are attached
& it can rotate plain polarized light to the right
or to the left.
 E.g. Open chain formula of Glucose contains 4
Asymmetric carbon atoms. (C2, 3, 4 & 5).
 E.g. Close chain formula of Glucose contains 5
Asymmetric carbon atoms. (C1, 2, 3, 4 & 5).
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Optical Isomers
 Those sugars which rotates plain
polarized light to right are (d) sugars &
which to left are (l) sugars.
Racemic Mixture:
 Such a solution which contains equal
amount of Levo & dextro-rotatory then
rotation of light will be equal but in
opposite direction.
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Ring Structure
 Hemiacetal ring: if the ring is formed by
aldehyde gp.
 Hemiketal ring: if the ring is formed by
keto gp.
 Pyranose Ring: 6 sided ring. O2 bridge
b/w C1 & C5.
 Furanose Ring: 5 sided ring. O2 bridge
b/w C1 & C4.
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Anomeric carbon
 C of Aldehyde or keto gp forming
hemiacetal or Hemiketal rings.
 C1 in Aldo-sugars. E.g. glucose
 C2 in keto sugars. E.g. fructose
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Mutarotation
 The direction of plain polarized light in a
freshly prepared glucose solution goes
on changing for some time before settling
to specific direction.
 Reason: unfolding of ring structure to
striaght chain in order to maintain
equilibrium b/w α & β forms of sugars.
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Phenomenon of Inversion
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