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Carbohydrates-CND.ppt
1. CARBOHYDRATES
Carbohydrates are the most abundant organic
molecules in nature.
Carbo-Hydrates means “Hydrates of carbon.” also
called saccharides, which means “sugars.”
Carbohydrates are defined as polyhydroxyaldehydes or
polyhydroxyketones or compounds which produce
them on hydrolysis.
1
Composed
of
Sulphur, Nitrogen or
Phosphorus
-carbon
hydrogen
oxygen
2. They act as storehouses of chemical energy (glucose, starch,
glycogen); are the components of supportive structures in plants
(cellulose), crustacean shells (chitin) and connective tissues in
animals (acidic polysaccharides) and are essential components of
nucleic acids (D-ribose and 2-deoxy-D-ribose).
Carbohydrates make up about three fourths of the dry weight of
plants.
But in animals it is less than 1%.
General molecularformula - CnH2nOn
Several non-carbohydrates compound are (acetic acid C2H4O2 and
lactic acid C3H6O3) also appear as hydrates of carbon. But, some
of genuine carbohydrates(rhamnohexose (C5H10O4) and
deoxyribose (C6H12O5) Do not satisfy the general formula.
3. Animals get their carbohydrates by
eating plants but they do not store
much, than they consume.
Carbohydrates are produced by
photosynthesis in plants, such as
glucose are synthesized in plants
from CO2, H2O, and energy from
the sun. Then, are oxidized in living
cells to produce CO2, H2O, and
energy.
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4. Each year, 100 metric tons of CO2 is converted to
Carbohydrates by plants
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5. Classification of Carbohydrates
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Disaccharides
2 sugar units
Oligosaccharides
3-10 units
Polysaccharides
>10
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e.g.Glucose,
fructose etc
e.g.Sucrose
e.g. Maltotriose
Heteroglycans
e.g. GAGs or
glycosaminoglycans
Homoglycans
e.g. Starch or glycogen
6. • 1. Monosaccharides
• Carbohydrates that cannot be hydrolysed into simpler carbohydrates
are called as monosaccharides.
• Sucrose (C12H22O11)+ H2O acid or certain enzyme_ Glucose +
fructose
• Structure and Nomenclature:
The general formula CnH2nOn
Withone of the carbons being the carbonyl group of either an aldehyde
or a ketone.
The most common monosaccharides have three to eight carbon atoms.
The suffix-ose indicates that a molecule is a carbohydrate, and the
prefixes tri, tetr-, pent-, and so forth indicate the number of carbon
atoms in the chain like, triose, tetrose, pentose, etc.
Monosaccharide containing an aldehyde group are classified as aldoses;
those containing a ketone group are classified as ketoses.
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7. Dr.S.P.Preethi
• Monosaccharide further classified on the basis of
functional group and number of carbon atoms present in their
structure
On the basis of no. of carbon atom On the basis of functional group
No.of
Carbon
atoms
Generic
name
ALDOSE KETOSE
3 Trioses
Aldotriose e.g.
glyceraldehyde
Ketotriose e.g.
Dihydroxyacetone
4 Tetroses
Aldotetrose e.g.
Erythrose
Ketotetrose e.g.
Erythrulose
5 Pentoses
Aldopentoses e.g
Arabinose, Xylose,
Ribose
Ketopentoses e.g.
Xylulose, Ribulose
6 Hexoses
Aldohexose e.g.
Glucose,
Galactose,
Mannose
Ketohexose e.g. Fructose
7 Heptoses
Aldoheptose:
Glucoheptose
Ketoheptose e.g
Sedoheptulose
8. Dr.S.P.Preethi
Stereoisomerism:
Compounds having same structural formula, but differing in spatial
configuration as known as stereoisomers.
Asymmetric carbon/ Chiral carbon: Four different groups are
attached to the same carbon.
The number of asymmetric carbon atoms (n) determines the possible
isomers of a given compound which is equal to 2n e.g. glucose contains
4 asymmetric carbons thus having 16 isomers.
The reference molecule is glyceraldehyde.
All monosaccharides can be considered as molecules derived from
glyceraldehyde by successive addition of carbon atoms.
Structural aspects of monosaccharides
9. D and L Isomers are mirror images of each
other.:
The spatial orientation of H & OH groups
on the C- atom (C5 for glucose), adjacent
to the terminal primary alcohol carbon
determines whether the sugar is D or L
Isomer.
If the OH group is on the right side, the
sugar is of D- Isomer. If the OH group is on
the Left side, the sugar is of L- Isomer.
Mammalian tissues have D- sugars.
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D- and L- isomers
13. Optical activity/ Optical Isomerism
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Optical activity is a characteristic feature of compounds
with asymmetric carbon atom. Carbon atom can have four
different groups then the carbon atom will possess
asymmetry.
A carbon atom is said to be asymmetric when its mirror
images are non-super imposableon each other.
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14. These types of compounds are called enantiomeric
pair , the have identical physical properties but they
interact differently with polarized light.
When a beam of polarized light is passes through a solution of an
optical isomer, it will be rotated either to the right or left. Depending
on the rotation, molecules are called dextrorotatory (+) or
levorotatory (-).
The optical rotation is measured by an instrument called polarimeter.
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15. Racemic mixture:
If D & L isomers are present in equal concentration, it is known
as racemic mixture.
NOTE: Racemic mixture does not exhibit any optical activity,
since the dextro and levorotatory activities cancel each other.
Specific rotation of some sugars
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16. Dr.S.P.Preethi
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Epimers
If two monosaccharides differ from each other in their configuration
around a single specific carbon atom, they are referred as epimers to
each other.
Glucose & galactose are C4-epimers. Glucose & mannose are C2-
epimers
Inter-conversion of epimers is known as epimerization, epimerase
catalyze this reaction.
17. Anomerism – Mutarotation
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Anomers have same composition but differ in the orientation of
groups around anomeric carbon atom.
Anomeric carbon is a hemiacetal or carbonyl carbon atom, e.g. 1st
carbon atom in glucose is anomeric carbon atom.
Carbonyl carbon atom becomes asymmetric because of ring
structures of monosaccharides in solution thus anomers are
encountered in cyclic structures of monosaccaharides.
The alpha & beta cyclic forms of D-glucose are known as
Anomers.
They differ from each other in the configuration only around
C1 known as anomeric carbon.
In case of alpha anomer, the OH group held by anomeric carbon is
on the opposite side of the group CH2OH of sugar ring.
18. Anomers are expressed as α and β forms.
In α form “OH” group is below the plane (OH group is oriented
away from the oxygen atom).
In β form “OH” group is above the plane (OH group is oriented
towards the oxygen atom).
Mutarotation:
When D-glucose is crystallized at room temperature and a fresh
solution is prepared, its specific rotation of polarized light is
112o; but after 12- 18 hrs it changes to +52.5 o
Mutarotation is defined as the change in the specific
optical rotation representing the interconversion of α and
β forms of D-glucose to an equilibrium mixture. 18
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20. Cyclization
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Less then 1% of CHO exist in an open chain form.
Predominantly found in ring form.
Involving reaction of C-5 OH group with the C-1 aldehyde
group or C-2 of keto group.
Six membered ring structures are called Pyranoses.
Five membered ring structures are called Furanoses.
Straight chain form
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21. PROPERTIES OF MONOSACCHARIDES
1. Physical properties:
Monosaccharides are colourless, crystalline compounds, readily
soluble in water and sweet in taste. Their solutions are optically
active and exhibit mutarotation.
2.Chemical properties:
a)Reduction: When treated with reducing agents such as sodium
amalgam, hydrogen can reduce sugars. Aldose yields
corresponding alcohol. Ketoses form two alcohols
because of appearance of new
b) asymmetric carbon in this process.
D-Glucose D-Sorbitol
D-Fructose D-Sorbitol+D-Mannitol
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22. b) Oxidation: upon oxidation aldose sugars like glucose yields
carboxylic acid, the aldehyde group is oxidized to carboxyl group to
produce respective acids.
Glucose Gluconic acid
Mannose Mannonic acid
Galactose Galactonic acid
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23. c) Formation of esters: Hydroxyl groups of sugars can be esterified
to form acetates, propionates, benzoates, etc. Sugar phosphates are
of great biological importance. Metabolism of sugars inside the
body starts with phosphorylation.
e.g Glucose 6-P04
d) Formation of osazone: this test is given by reducing sugar like,
glucose, fructose, lactose and maltose. In this test phenyl hydrazine
is reduced to phenyl hydrazone by sugar solution. Phenyl hydrazone
when heated with more amount of phenyl hydrazine forms yellow
crystals of osazone.
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24. e) Furfural formation/Dehydration: Monosaccharides when
treated with concentrated H2SO4 undergoes dehydration with the
removal of 3 molecules of water. Hexoses give hydroxymethyl
furfural and pentoses give furfural. Furfurals condense with phenolic
compounds to give various colors.
E.g. Molisch’s test: General test for carbohydrates (H2SO4 and α-
naphthol). Rapid Furfural and Seliwanoff ’s test: Tests for presence
of keto group
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27. Dr.S.P.Preethi
When two monosaccharides (similar or dissimilar) arecombined
togetherby glycosidic linkage, a disaccharide is formed.
All are isomers with molecular formula C12H22O11
On hydrolysis they yield 2 monosaccharide which soluble in water
Even though they are soluble in water, they are too large to pass
through the cell membrane.
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Sucrose
Trehalose
Cane
sugar in
yeast
Reducing
Lactose
Maltose
Milk
sugar
Malt
sugar
There are two type
Non-reducing
28. Condensation and Hydrolysis—Forming and
Breaking Glycosidic Bonds
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• The –OH group that is most reactive in a monosaccharide is the
one on the anomeric carbon.
When this hydroxyl group reacts with another hydroxyl
group on another monosaccharidea glycosidic bond is formed.
• During this reaction, a moleculeof water is eliminated as two
molecules join.
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29. • Condensation reaction is a type of reaction that occurs when
two molecules are joined and a water molecule is produced. This
type of reaction is referred to as a dehydration reaction.
• Condensation reactions occur between different types of
functional groups that contain an –H in a polar bond, like O–H
or N–H, and an –OH group that can be removed to form water.
• Hydrolysis reaction is the reverse of a condensation reaction.
• A larger moleculeforms two smaller molecules and water is
consumed as a reactant.
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30. In the case of maltose, the glycosidic bond is specified as α(1→4)
and is simply stated as alpha-one-four.
• If the –OH group had been in the beta configuration when the
glycosidic bond was formed, the bond would be in the β(1→4)
configuration. The molecule formed would be named cellobiose
and would have a different two-dimensional and three-
dimensional shape than maltose.
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Maltose
31. Sucrose (glucose+ fructose)
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• Sucrose is known as table sugar.
• It is the most abundant disaccharide found in nature.
• Sucrose is found in sugarcane and sugar beets.
• The glycosidic bond is α β (1→ 2).
• Both anomeric carbons of the monosaccharides in sucrose are
bonded, therefore, sucrose is non-reducing sugar. It will not
react with Benedict’s reagent. Also it not form osazone crystals
in osazone test.
• When hydrolyzed, it forms a mixture of glucose and fructose
• Clinical Importance:-
-dental caries
-Bypasses metabolic check points- OBESITY
-Sucrase deficiency
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32. Inversion of Sucrose
Hydrolysis of sucrose (optical rotation +66.5o) will produce
one molecule of glucose (+52.5o) and one moleculeof fructose
(-92o)
• Therefore theproducts will change thedextrorotation
to levorotation
(INVERSION)
• Equimolecular mixture of glucose and fructose thus formed
is called as Invert Sugar
• The enzyme producing hydrolysis of sucrose is called
INVERTASE
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33. Maltose (glucose+ glucose)
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• Maltose is known as malt sugar.
• 2 glucose residues α (1 → 4) linkage
• Another form is α (1 → 6) called as Isomaltose.
• It is formed by the breakdown of starch. Malted barley, a key
ingredient in beer, contains high levels of maltose.
• During germination of barley seeds, the starch goes through
hydrolysis to form maltose.
• This process is halted by drying and roasting barley seeds
prior to their germination.
• One of the anomeric carbons is free, so maltose is a reducing
sugar.
Osazone test:- Starshaped or flower petal shaped
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34. Lactose (galactose+ glucose)
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• Lactose is known as milk sugar.
• It is found in milk and milk products.
• The glycosidic bond is (1→4).
• An intolerance to lactose can occur in people who inherit or
lose the ability to produce the enzyme lactase that hydrolyzes
lactose into its monosaccharide units.
• One of the anomeric carbons is free, so lactose is a reducing
sugar.
• Osazone test – Powder Puff or hedge hog shaped
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35. Homoglycan Or
Homopolysaccharide
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Heteroglycan Or
Heteropolysaccharide
3. Polysaccharides
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Polysaccharides are large molecules containing 10 or more
monosaccharide units. Carbohydrate units are connected in
one continuous chain or the chain can be branched.
1. Storage polysaccharides contain only α- glucose
units. Three important ones are starch, glycogen, and
amylopectin.
2. Structural polysaccharides contain only β- glucose
units. Two important ones are cellulose and chitin.
Chitin contains a modified β- glucose unit.
36. Homopolysaccharides (all one type of monomer), e.g.,
glycogen, starch, cellulose, chitin, inulin, dextran.
Heteropolysaccharides (different types of monomers),
e.g., peptidoglycans, glycosaminoglycans
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Branched
polysaccharides 36
Unbranched/ Linear
polysaccharides
38. Starch
Carbohydrates of the plant kingdom
Sources: Potatoes, tapioca, cereals (rice, wheat) and other food
grains
Starch is a homopolymer composed of D-glucose units held
by α-glycosidic bonds.
Composed of two polysaccharide components-Amylose &
Amylopectin
Amylose:
Amylose makes up 20% of plant starch and is made up of 250–
4000 D-glucose units bonded α (1→4) in a continuous chain.
Long chains of amylose tend to coil.
Mol wt =400,000 or more
It is water soluble
HOMOPOLYSACCHARIDES
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α -amylose
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39. Amylopectin:
•The insoluble gel; part absorbs water and forms paste
like, Amylopectin makes up 80% of plant starch and made up of
glucose units, but is highly branched with molecular weight more
than 1 million.
•The branching points are made by α- 1, 6 linkage
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40. Hydrolysis of Starch
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About every 25 glucose units of amylopectin, a branch of glucose
units are connected to the glucose by an α(1→6) glycosidic bond.
During fruit ripening, starch undergoes hydrolysis of the
α(1→4) bonds to produce glucose and maltose, which are sweet.
When we consume starch, our digestive system (α-amylase)breaks it
down into glucose units for use by our bodies.
Starch will form a blue coloured complex with iodine; this color
disappears on heating and reappears when cooled. This is a sensitive
test for starch.
When starch is hydrolyzed by mild acid, smaller and smaller
fragments are produced.
The hydrolysis for a short time produces amylodextrin (violet color
with iodine and non-reducing).
Further hydrolysis…………….amylodexerythrodexarchrodextrin
Maltose
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41. Glycogen
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Storage form of energy in animal. Stored in liver and muscle
Stores more glucose residues per gram than starch.
More branched and compact than starch.
A homopolysaccharide (number of glucose units upto 25000):
linear chain of α (1→4) linked glucosyl residues with branches
joined by α (1→6) linkages
More energy in a smaller space.
Glycogen in liver (6-8%) is higher than that in the muscles (1-
2%).
Liver glycogen - first line of defense against declining blood
glucose levels especially between meals.
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42. Cellulose
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Glucose units combined by β-1,4 linkages.
Straight line chain with no branches. This allows chains to
align next to each other to form a strong rigid structure.
Mol wt 2-5 million.
• Cellulose is an insoluble fiber in our diet because we lack the
enzyme cellulase to hydrolyze the β-1,4 glycosidic bond.
• Whole grains are a good source of cellulose.
• Cellulose is important in our diet because it assists with
digestive movement in the small and large intestine.
• Some animals and insects can digest cellulose because they
contain bacteria that produce cellulase.
• Commercial applications: nitrocellulose, cellulose acetate
membranes for electrophoresis.
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43. Chitin
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•Chitin makes up the exoskeleton of insects and crustaceans and cell
walls of some fungi.
• It is made up of N-acetyl glucosamine containing β(1→4) glycosidic
bonds.
• It is structurally strong.
• Chitin is used as surgical thread that biodegrades as a wound heals.
• It serves as a protective Exoskeleton in crustacea and insects.
• Chitin is also used to waterproof paper, and in cosmetics and lotions
to retain moisture.
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44. Dextrins/Dextrans
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Highly branched homoglycan containing Glucose residues in 1-6,
1-4 and 1-3 linkages.
Produced by microbes.
Mol. wt:- 1-4 million.
As large sized, they will not move out of vascular compartment
so used as plasma expanders.
Inulin
• D -fructose in β-1,2 linkages.
• Source: Bulbs and tubers chicory, dahlia, dandelion, onions,
garlic.
• Not metabolized .
• Not absorbed nor secreted by kidneys so, used to measure GFR.
45. HETEROPOLYSACCHARIDES
Polymers made from more than one kind of monosaccharides or
monosaccharide derivatives. e.g., mucopolysaccharides, Agar & Agarose
and glycoproteins.
MUCOPOLYSACCHARIDES
First isolated from mucin so called mucopolysaccharides
Long, Unbranched heteropolysaccharide, made of repeating disaccharide
units containing uronic acid & amino sugars. These are more commonly
known as Glycosaminoglycans (GAG).
Amino sugar – Glucosamine or Galactosamine (Present in there acetylated
form)
Uronicacid – D-Glucuronic acid
Major components of extracellular matrix of connective tissue, including
bone and cartilage, synovial fluid, vitreous humor and secretions of mucus
producing cells.
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46. Sulfate containing Chondroitin Sulphate, Dermatan
sulphate, keratan sulphate, Heparin,
Heparan Sulphate
Hyaluronic acid:
It is the simplest mucopolysaccharide and is a linear
polymer of disaccharides which form the repeating unit.
Each disaccharide is linked to the next by β- 1,4 glycosidic
bonds. It consists of two alternative units of D-glucuronic
acid and N-acetyl D-glucosamine, linked by β-1,3 to give a
thread like structure.
Present in Synovial fluid of joints, vitreous humor, connective
tissues and cartilage.
Sulfate free Hyaluronic acid
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47. Functions:
•Serves as a lubricant and shock absorbant in joints.
•Acts as seives in extracellular matrix.
•Permits cell migration during morphogenesis & wound repair.
•Hyaluronidase is an enzyme that breaks β1 – 4 linkages of hyaluronic
acid.
•Present in high concentration in seminal fluid, & in certain snake and
insect venoms. Hyaluronidase enzyme of semen degrades the gel
around ovum & allows effective penetration of sperm into ovum, thus
helps in fertilization.
Condroitin sulphates
Widely distributed in bone, cartilage, skin, heart & tendons. The
repeating unit is a disaccharide and consisting of alternate units of D-
glucuronic acid linked to sulphate ester of N- acetyl galactosamine.
Functions:
•In cartilage, it binds collagen & hold fibers in a tight strong network.
•Role in Compressibility of cartilages in weight bearing. 46
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48. Heparin
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Heparin is a medically important polysaccharide because it
prevents clotting in the bloodstream.
It is a highly ionic polysaccharide of repeating disaccharide units of
an oxidized monosaccharide and D-glucosamine. Heparin also
contains sulfate groups that are negatively charged.
present intracellular: In granules of mast cells and also in lung, liver
and skin.
Functions:
• It is an anticoagulant (prevents blood clotting)
• Heparin helps in the release of the enzyme lipoprotein lipase
(LPL) which helps to clear the lipidemia after fatty meal – so
called clearing factor.
49. AGAR
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Contains galactose, glucose & other sugars. Obtained from
sea weeds
Functions:
• Cannot be digested by bacteria. So used as
supporting agent to culture bacterial colonies.
• Also as support medium of immuno diffusion & immuno-
electrophoresis.
AGAROSE
Galactose and 3,6 anhydrous galactose units. Used as matrix
for electrophoresis.
50. • GLYCOPROTEINS
• Several proteins are covalently bound to carbohydrates which are
referred to as glycoproteins. The carbohydrate content of
glycoproteins varies from 1% to 90% by weight. The term
mucoprotein is used for glycoproteins with carbohydrate
concentration more than 4%.
• Glycoproteins are very widely distributed in the cells and perform
variety of functions like enzymes, hormones, transport proteins,
structural proteins, blood group antigens and receptors.
• The carbohydrates found in glycoproteins include mannose,
galactose, N-acetyl glucosamine, N-acetyl galactosamine, xylose
and N-acetyl neuraminic acid (NANA)
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51. Qualitative tests for Carbohydrates
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To study the properties of carbohydrates.
To identity of an unknown carbohydrate by carrying out a series
of chemical reactions
1. SOLUBILITY (to differentiate mono and disaccharides from
polysaccharides)
Mono and disaccharides are soluble in water to give clear
solution. Whereas, polysaccharides are insoluble in water.
2.MOLISCH TEST (for all carbohydrates)
Principle: Carbohydrates when treated with concentrated
sulphuric acid undergo dehydration to derivatives. These
compounds condense give furfural with Alpha
naphthol to form colored products. Pentoses yield furfural
while Hexoses yield 5-Hydroxy methyl furfurals.
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52. This is a sensitive but a non- specific test and is given positive by
all types of carbohydrates.
If the oligosaccharides or polysaccharides are present they are
first hydrolysed to monosaccharides which are then dehydrated
to give the test positive.
3. BENEDICT’S TEST (to differentiate reducing sugars from
non- reducing sugars)
-Carbohydrates with free aldehyde or ketone groups have the ability
to reduce solutions of various metallic ions.
Reducing sugars under alkaline conditions tautomerise and form
enediols.
-Enediols are powerful reducing agents.
They reduce cupric ions to cuprous form themselves
and are converted to sugar acids.
-The cuprous ions combine with OH- ions to form yellow
cuprous hydroxide which upon heating is converted to red
cuprous oxide.
-
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53. 4.FEHLING’S and TOMMER’S TEST (to differentiate
reducing sugars from non-reducing sugars)
Reducing sugar reduces copper ions present in the
Fehling solution so as to give red precipitate
5. BARFOED’S TEST (to differentiate
monosaccharides from disaccharides )
Aldoses and ketoses can reduce cupric ions even in
acidic conditions. This test is used to distinguish
reducing monosaccharides from disaccharides by
controlling pH and time of heating.
Monosaccharides react very fast whereas
disaccharides react very slowly. The positive
reaction indicates the presence of a reducing
monosaccharide. On prolonged heating
disaccharides can also give this test positive.
Hence, the solution should be boiled for 3
minutes only. 51
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54. 6. SELIWANOFF’S and RAPID
FURFURAL TEST (to differentiate
ketoses from aldoses)
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Keto hexoses on treatment with hydrochloric acid
form 5-hydroxy methyl furfural which
condensation on resorcinol gives a with colored
complex cherry red
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7. HYDROLYSIS OR INVERSION TEST (to
confirm sucrose)
Sucrose is a non-reducing sugar, since it does not
have free aldehyde or ketone group to cause
reduction, hence it gives a negative reaction
with Benedict’s reagent.
But upon boiling with HCl, sucrose is hydrolyzed
to yield glucose and fructose, which give positive
reactions with benedict and Seliwanoff reagents.
55. 8. OSAZONE TEST (todifferentiateamong reducing
sugars by their crystalline structure)
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A solutionof reducing sugar when heated with
phenyl hydrazine, Characteristic yellow crystalline
compounds called Osazone are formed.
These crystals have definite crystalline structure,
precipitation time and melting point for different reducing
sugars.
Needle shaped
glucosazone
crystals as viewed
under the
microscope
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Galactosazone
crystals as viewed
under the
microscope(Rhom
bic plates)
Sun flower
shaped
Maltosazone
Powder puff/hedge
hog shaped
Lactosazone
56. 9. IODINE TEST (for all polysaccharides)
Iodine forms a coordinate complex between the
helically polysaccharide chain coiled due to iodine
centrally located within the helix adsorption.
The color obtained depends upon the length of
chain the unbranched or linear available for
complex formation
Left to right: Lugol's iodine, starch solution, starch solution with iodine.
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57. Diseases related to Carbohydrates metabolism
1) Diabetes mellitus (D.M.)
•When the body is unable to utilize the glucose then there is an
appearance of excessive sugar in the blood, as well as in the urine called
glycosuria and the disease is termed as diabetes mellitus.
•It is a group of metabolic disorders with a common characteristic
feature of hyperglycemia.
•The blood sugar level is regulated by the pancreatic protein hormone
insulin, which is secreted by the β- cells of islets of langerhans of
pancreas.
•Hyperglycemia in D.M. Is due to defect in insulin action, secretion or
both.
Diabetes mellitus is broadlyclassified into 2 categories:
a)Type 1 diabetes: it is characterised by absolute deficiency of insulin
due to destruction of β- cells of pancreas.
b)Type 2 diabetes: it is caused due to peripheral resistance to insulin
action and inadequate secretion of insulin by β- cells of pancreas.
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58. The blood glucose level rises remarkably (>200 mg/dl) than
normal (70-120 mg/dl) in D.M.
Characteristics or Symptoms:
hyperglycemia(increased in blood sugar), glycosuria
(sugar in urine),
increased fat and protein metabolism, ketosis (increased in
ketone bodies in tissue), hypercholesterolemia (blood LDL
increased), atherosclerosis (plaque formation on the wall of
artery), polyuria (increased urine volume), polydipsia
(increased thirst), polyphagia (excessive ingestion of food),
coma and death.
Treatment: D.M., can be treated by administering insulin
subcutaneously or by giving oral antidiabetic/ oral
hypoglycemic agents. Patient may advised to take protein diet
but not the carbohydrate diet.
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59. 3) Galactosemia:
Due to deficiency of the enzyme galactose 1- phosphate uridyl
transferase and galactokinase, galactose cannot be converted
into glucose, which leads to a condition called as galactosemia.
It is characterized by increased galactose levels in blood and
urine. Accumulated galactose is converted into galactitol,
which is responsible for development of cataract.
The clinical symptoms of galactosemia are jaundice,
hepatospleenomegaly, mental retardation, etc.
4) Fructose intolerance:
One of the very normal hexose sugar of fruits (i.e. Fructose)
gets normally metabolised to give energy and CO2, but
defective metabolism of fructose develop in high concentration
of this sugar in blood, disorder known as fructose intolerance.
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Dr.S.P.Preethi
60. 5) Glycogen storage diseases:
59
The metabolic abnormalities related withglycogen synthesis and
degradation are collectively termed as glycogen storage diseases.
These are:
a) Van glerke’sdisease: it is due to hepatic glycogen storage.
b)Pompe’s disease: it is due to storage of normal glycogen in almost
every organ of the body, including the heart.
c) Limit dextinosis; forbe’s or cori’s disease: it is due to increased
deposition of glycogen with very outer branches in the liver and
other tissues.
d)Amylopectonosis or anderson’s disease: it is due to
deficiency of branching enzymes which results in accumulation
of glycogen.
Dr.S.P.Preethi
61. Functions/ Role of Carbohydrates
Dr.S.P.Preethi
60
• Serve as main sources of ENERGY in body (4kcal/g)
1) As structural component: Carbohydrates are the essential
components of some structural materials of living organisms:
2) Monosaccharides act as a constituents of nucleic acids,
coenzymes,
f lavoproteins and blood group substances.
- Immuno-polysaccharides play an importantrole in the
resistance of infections.
- Hyaluronic acid is a viscous substance in the matrix of connective
tissue and various other tissues, acts as a good lubricant.
- Heparin, is a naturally occuring anticoagulant, prevents blood
coagulation.
- glucoronic acid, acts as detoxifying agent by forming complex
with toxic substances.
- Glycosides are the components of steroid hormones,
act as cardiotonic agent.
-
62. 2) Supply and storage of energy:
carbohydrates, supplies and stores energy. About 60% of energy is supplied
by the catabolism of carbohydrates.
1 gm of carbohydrates on oxidation gives 4 calories of energy.
Glucose is the sole form of energy for the brain and nervous tissues.
stored glycogen, in the liver, also provides energy in absence of glucose.
3)Regulates fat metabolism:
carbohydrates are required for the normal oxidation of fats.
In the absence of carbohydrates, fat deposition occurs in the body and may
give risk to ketosis.
4) Carbohydrates provides essential energy to the body by sparing protein for
building of tissues.
5)It also plays a role in gastrointestinal functions.
Polysaccharides like cellulose, pectin give bulk and help in the peristaltic
movements of the digestive tract.
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63. REFERENCE
:
Dr.S.P.Preethi
62
1.Morrison, R.I. and Boyd, R.N. Organic chemistry, 5th ed. Prentice-Hall of India,
New Delhi, 1989
2.Robert Boxer. 1997. Essentials of organic chemistry; the Mcgraw-Hill companies,
Inc
3.Finar I.L. Organic chemistry, Vol I and II, 6th ed. Longman, 1985. 4.Jerry March , “
ADVANCED ORGANIC CHEMISTRY ”
5. Kadam, Principles of Organic Chemistry.
