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naturally occurring polyhydroxy aldehydes or ketones or substances which
yield such compounds on hydrolysis are called carbohydrates.
Classification of Carbohydrates.
are classified as sugars and non-sugars.
Basic units cannot be further
Contains 5 C - atoms. Example: Ribose C5H10O5
Contains 6 C - atoms. Example: Glucose C6H12O6
Contains 5 C - atoms. Example: Ribulose C5H10O5
Contains 6 C - atoms. Example: Fructose C6H12O6
Can be hydrolysed to give 2 - 10 units of
2 molecules of monosaccharides of
hydrolysis. Example: Sucrose C12H22O11
3 molecules of monosaccharides on
hydrolysis. Example: Raffinose C18H32O16
Example: Starch, cellulose (C6H10O5)x
Preparation of Glucose (C6H12O6)
From sucrose i.e., cane sugar (in laboratory)
From starch (large scale preparation)
naturally occurring nitrogen containing polymeric compounds of very high
molecular weight containing recurring - CONH - group are called proteins.
Classification of Proteins:
Simple Proteins: Examples: Albumin, globulin.
On hydrolysis, they give only a - amino acids.
Globular Proteins: Example: Albumin
These proteins are spherical in shape and are soluble in water.
Fibrous or Structural Proteins: Examples:
These proteins have fibre-like structures and are insoluble in water.
Conjugated Proteins: Example: Nucleoprotein.
On hydrolysis, they give a - amino acids and some non-protein
compound (prosthetic group).
Derived Proteins: Examples: Polypeptides, peptones.
These proteins are formed by the treatment of some chemicals or heat on
- CONH linkage
which joins a-amino acids in the structure of protein is known as a
It is formed by the combination of the amino group of one a-amino acid with
the carboxyl group of the other a-amino acid.
Colour Test of Proteins
A protein solution is heated with 10% NaOH solution. A drop
of aq. CuSO4 solution is added to the hydrolysed protein
solution. A reddish - violet colour develops showing presence of
Millon's reagent is a solution of mercurous nitrate and
mercuric nitrate in dilute HNO3.
When a protein solution is warmed with Millon's reagent, a white
precipitate is formed, which turns red on boiling. This shows the
presence of phenolic -OH group in the protein molecule.