(i) Homopolysaccharides are composed of only one type of monosaccharides. E.g. Starch, cellulose and glycogen.
(ii) The heteropolysaccharides are composed of more than one. E.g. Hyaluronic acid, heparin.

Polysaccharides are called as non-sugars since they don't have an sweet taste.

In sucrose, C₁ of o-D-glucose is joined to C₂ of -D-fructose. The glycosidic bond thus formed is called 0-1,2 glycosidic bond. Since, the both the carbonyl carbons (reducing groups) are involved in the glycosidic bonding, sucrose is a nonreducing sugar.

When pure form anyone of these sugars dissolved in water, slow interconversion of a-D glucose and ²-D glucose via open chain form until equilibrium is established giving constant specific rotation + 53°. This phenomenon is called mutarotation.

Fructose is prepared commercially by hydrolysis of Inulin (a polysaccharide) in acidic medium.
\(\underset { Inulin }{ \left( { C }_{ 6 }{ H }_{ 12 }{ O }_{ 5 } \right) _{ 5 } } +n{ H }_{ 2 }O\overset { { H }^{ + } }{ \longrightarrow } \underset { Frutose }{ { nC }_{ 6 }{ H }_{ 12 }{ O }_{ 6 } } \)

Sugar differing in configuration at an asymmetric centre is known as epimers.

Anomers are cyclic monosaccharide differing from each other in the configuration of C₁ if they are aldoses or in the configuration of C₂ if they are ketoses.
E.g. α and βD - glucose.

Human blood contains about 100 mg/dL of glucose, hence it is also known as blood sugar.

On reduction with concentrated HI and red phosphorus at 373K, glucose gives a mixture of n hexane and 2, iodohexane indicating that the six carbon atoms are bonded linearly.

The process by which one epimer is converted into other is called epimerisation and it requires the enzymes epimerase. Galactose is converted to glucose by this manner in our body.

The type of sugar that contains 4 carbon atoms and -CHO group is Aldotetrose. Example of Aldotetrose is Erythrose.

(i) D isomer
(ii) Lisomer

Photosynthesis.

Lactose is a dissaccharide so on hydrolysis gives I two monosaccharides.
\(\underset { Lactose }{ { C }_{ 12 }{ H }_{ 22 }{ O }_{ 11 }+{ H }_{ 2 }O } \overset { + }{ \longrightarrow } \underset { D(+)G1ucoseD(+)Galactose }{ { C }_{ 6 }{ { H }_{ 12 }{ O }_{ 6 } }+{ C }_{ 6 }{ H }_{ 12 }{ O }_{ 6 } } \)