Notes On Proteins: Amino Acids - CBSE Class 12 Chemistry
Classification & Physical properties of Amino acids:
 
Amino acids are compounds that have one or more amino groups and carboxyl groups in a molecule. Amino acids are the building blocks of proteins. On the basis of relative position of amino group with respect to carboxyl group amino acids are classified into alpha, beta, gamma etc…..
 
...
 
Only alpha-amino acids are found in naturally occurring proteins. Among the natural amino acids, that can be synthesised in the body are called non-essential amino acids
EX: alanine, serine and tyrosine

 
Whereas the amino acids that cannot be synthesised in the body and must be supplied in the diet are called essential amino acids
EX: Histidine, tryptophan and methionine.


 
On the basis of their nature Amino acids can be classified into to 3-types. They are,
  • ACIDIC AMINO ACIDS
  • BASIC AMINO ACIDS
  • NEUTRAL AMINO ACIDS


 
Physical properties of amino acids:
 
In general, amino acids in their pure states are colourless, crystalline solids. They are water-soluble with high melting points.  Most amino acids behave like salts rather than simple amines or simple carboxylic acids. In aqueous solutions form “zwitterions”.

 
 
All alpha or naturally occurring amino acids are optically active. Glycine does not have an asymmetric carbon hence it is optically inactive.

Summary

Classification & Physical properties of Amino acids:
 
Amino acids are compounds that have one or more amino groups and carboxyl groups in a molecule. Amino acids are the building blocks of proteins. On the basis of relative position of amino group with respect to carboxyl group amino acids are classified into alpha, beta, gamma etc…..
 
...
 
Only alpha-amino acids are found in naturally occurring proteins. Among the natural amino acids, that can be synthesised in the body are called non-essential amino acids
EX: alanine, serine and tyrosine

 
Whereas the amino acids that cannot be synthesised in the body and must be supplied in the diet are called essential amino acids
EX: Histidine, tryptophan and methionine.


 
On the basis of their nature Amino acids can be classified into to 3-types. They are,
  • ACIDIC AMINO ACIDS
  • BASIC AMINO ACIDS
  • NEUTRAL AMINO ACIDS


 
Physical properties of amino acids:
 
In general, amino acids in their pure states are colourless, crystalline solids. They are water-soluble with high melting points.  Most amino acids behave like salts rather than simple amines or simple carboxylic acids. In aqueous solutions form “zwitterions”.

 
 
All alpha or naturally occurring amino acids are optically active. Glycine does not have an asymmetric carbon hence it is optically inactive.

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