The document discusses carbohydrates, which are a major source of energy composed of carbon, hydrogen, and oxygen. They include monosaccharides (simple sugars), disaccharides (two monosaccharides joined), oligosaccharides (3-10 monosaccharides), and polysaccharides (long chains of monosaccharides). Important monosaccharides include glucose, fructose, and galactose. Disaccharides formed from two monosaccharides include maltose, lactose, and sucrose. Polysaccharides are polymers of monosaccharides and include starch, glycogen, and cellulose. Carbohydrates have important biomedical roles as energy sources and structural components in the body.
4. CARBOHYDRATES
Carbohydrates are aldehyde or ketone compounds
with multiple(two or more)hydroxyl groups.
They are polyhydroxylated compounds with
atleast three carbon atoms, with potentially active
carbonyl groups which may either be aldehyde or
ketone groups.
The term applied to a large number of relatively
heterogeneous compounds found in all animals
and plants.
Carbohydrates including sugars are also called
saccharides(saccharide=sugar).
8. MONOSACCHARIDES:
Also called simple sugars ,are those which can not be
hydrolyzed further into simpler forms.
General formula------------CnH2nOn
They can be subdivided further ,
A) Depending upon the number of carbon atoms
they possess ,as
trioses,tetroses,pentoses,hexoses,etc.
B) Depending upon whether aldehyde(-CHO) or
ketone(-CO) groups are present as aldoses or ketoses
9. Aldoses
9
Aldoses are
monosaccharides
With an aldehyde group.
With many hydroxyl
(─OH) groups.
triose (3 C atoms)
tetrose (4 C atoms)
pentose (5 C atoms)
hexose (6 C atoms)
O
║
C─H aldose
│
H─ C─OH
│
H─ C─OH
│
CH2OH
Erythose, an aldotetrose
10. Ketoses
10
Ketoses are
monosaccharides
With a ketone group.
With many hydroxyl
(─OH) groups.
triose (3 C atoms)
tetrose (4 C atoms)
pentose (5 C atoms)
hexose (6 C atoms)
CH2OH
│
C=O ketose
│
H─ C─OH
│
H─ C─OH
│
H─C─OH
│
CH2OH
Fructose, a ketohexose
11. Learning Check
Identify each as aldo- or keto- and as tetrose, pentose,
or hexose:
A B
H
CH2OH
OHC
H
H
H
OH
OH
OH
C
C
C
HC
O
CH2OH
HHO
CH2OH
O
H OHC
C
C
11
16. D-Galactose
D-galactose is
An aldohexose
C6H12O6.
Not found free in
nature.
Obtained from lactose,
a disaccharide.
A similar structure to
glucose except for the
–OH on C4.
H
H
H OH
CH2OH
C
HO
HO HC
OH
C
C
O
C H
D-Galactose
16
18. DISACCHARIDES:
Are those sugars which yield two molecules of the same
or different molecules of monosaccharide on hydrolysis.
General formula-----------Cn(H2O)n-1
Examples:
Maltose: Yields 2 molecules of glucose on hydrolysis.
Lactose: Yields one molecule of glucose and one
molecule of galactose on hydrolysis.
Sucrose: Yields one molecule of glucose and one
molecule of fructose on hydrolysis.
19. Important Disaccharides
19
A disaccharide
Consists of two monosaccharide.
Monosaccharide Disaccharide
Glucose + glucose maltose + H2O
Glucose + galactose lactose + H2O
Glucose + fructose sucrose + H2O
20. Maltose
20
Maltose is
A disaccharide also known as malt sugar.
Composed of two D-glucose molecules.
Obtained from the hydrolysis of starch.
Linked by an -1,4-glycosidic bond formed from
the
−OH on C1 of the first glucose and −OH on C4
of the second glucose.
Used in cereals, candies, and brewing.
Found in both the - and β - forms.
24. OLIGOSAACHRIDES:
Are those which yield 3 to 10 monosaccharides units
on hydrolysis,e.g.Maltotriose.
These are short chain condensation products of two
to ten monosaccharide units or residues joined to
each other covalently through O- glycoside bonds or
linkages.
Some oligosaccharides are,
α-dextrins (polymers of eight glucose units)
Maltotriose (has three glucose units)
Isomaltose
26. Polysaccharides
Polysaccharides
Are polymers of D-glucose.
Include amylose and
amylopectin, starches made
of α-D-glucose.
Include glycogen (animal
starch in muscle), which is
made of α-D-glucose.
Include cellulose (plants and
wood), which is made of
β-D-glucose.
O
CH2OH
OH
OH
OH
OH
26
α-D-glucose
27. POLYSACCHARIDES:(GLYCANS)
Are those which yield more than ten molecules of
monosaccharides on hydrolysis.
General Formula---------------(C6H10O5)n
Polysaccharides are further divided into two groups,
A) Homopolysaccharides (homoglycans):
Polymer of same monosaccharide units.
Examples:
Starch, glycogen, insulin, cellulose, dextrins, dextrans.
B) Heteropolysaccharides (heteroglycans):
Polymer of different monosaccharide units or their derivatives.
Examples:
Mucopolysaccharides (Glycosaminoglycans)
28. BIOMEDICAL IMPORTANCE OF
CARBOHYDRATES:
Chief source of energy
Constituents of compound lipids and conjugated proteins
Certain carbohydrate derivates are used as drugs like
cardiac glycosides/antibiotics
Lactose principal sugar of milk—in lactating mammary
glands.
Degradation products utilized for the synthesis of other
substances such as fatty acids, cholesterol, amino acids
etc.
Derangement of glucose metabolism is seen in Diabetic
mellitus.