Sources of Carbohydrate::
The best sources of carbohydrates are cereals like rice wheat millets like ragi maize roots and tubers like potato tapioca sweet potato yam and colocasia pulses sugar and jaggery honey fruit and vegetables are the other sources of carbohydrates Banana apple plantain and dried fruit are also good sources of carbohydrates
In an average indian diet carbohydrates are the cheap sources of calories one gram of carbohydrate gives 4 kcals and an average indian diet contains about 300 gms of carbohydrate
PROTEINS
Proteins are the essential constituents of protoplasm they differ from carbohydrates and lipids in that they contain nitrogen and hence cannot be replaced in diet by any other constituent the molecules are made up of a large number of amino acids joined together by peptide linkages (CO-NH)
The Chemistry of Proteins::
Proteins are complex organic compounds which contain carbon hydrogen oxygen nitrogen sulphur and phosphorus Certain proteins contain iron iodine copper and other inorganic elements the presence of nitrogen distinguishes protein from carbohydrate and fat protein contains an average of 16 percent nitrogen
A protein contains number of amino acids Two amino acids are linked together through peptide linkage in this the basic group of one amino acid combines with the carboxyl or acidic group of another group of amino acid two amino acids are linked together to form a dipeptide and it combines with another amino acid when a number od amino acids are linked together it is known as polypeptide
On hydrolysis large molecules of protein give out smaller units called amino acids Amino acids contain a carboxyl group (COOH) and an amino group (NH2) They are otherwise known as the acidic and basic group respectively there are twenty three amino acids in proteins Amino acids are grouped into five groups based on the number of amino groups and carboxyl group in them they are monoamino monocarboxylic acids monoamino dicarboxylic acids diamino monocarboxylic acids sulphur containing amino acids and aromatic and heterocyclic amino acids
1. monoamino -monocarboxylic acid
e.g. Glycine Alanine Valine Leucine Isoleucin
2. Monoamino -dicarboxylic acids
e.g. Aspartic acid Glutamic acid
3.Diamino monocarboxylic acid
e.g. Arginine Lysine
4.Sulphur containing amino acids
e.g. Cystine Cysteine Methionine
5. Aromatic and heterocyclic amino acids
e.g. Phenylalanine histidine tyrosine tryptophan proline Hydroxyproline
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