XII Chemistry BIEK Topic - Amino Acid (Short Note)

Amino Acid (Short Note)
Definition
Amino Acids are the common compounds which contain both carboxylic and amino group.

Carboxylic group is acidic whereas, the amino group is basic.




General Formula
The general formula of amino acid is

R-CNH2H-COOH

Where,

R = alkyl Group

NH2 = Amino Group

COOH = Carboxylic Group

These amino acids are also called α - amino acids because the amino groups is present on α - carbon atom to the carboxylic group.




Classification of Amino Acids
On the basis of number of carboxylic group (-COOH) and amino group (-NH2). Amino acids are classified into the following three classes.

1. Neutral Amino Acids

2. Acidic Amino Acids

3. Basic Amino Acids


1. Neutral Amino Acids

Those amino acids, which have equal number of -COOH and -NH2 groups, are called Neutral Amino Acids.


Example

1. Glycine (CH2NH2COOH)

2. Alanine (CH3-CH-NH2-COOH)


2. Acidic Amino Acids

Those amino acids, which have greater number of -COOH than -NH2 groups are called Acidic Amino Acids.


Example

1. Asparite [CH2NH2CH(COOH)2]

2. Glutamic [HOOC-CH2-CH2-CH-NH2-COOH]


3. Basic Amino Acids

Those amino acids, which cotain greater number of -NH3 than -COOH groups, are called Basic Amino Acids.


Example

1. Lysine [H2N-(CH2)4-CH-NH2-COOH]




Zwitter Ion
When the hydrogen ion of carboxylic group is accepted by amino group in amino acid then Zwitter ion is formed.

Zwitter ion is a German word, its meaning is two charged ion, i.e. both positive and negative charge. This ion is electrically neutral. In solution amino acid, exist in following ionic form.




Peptide Bond Or Peptide Linkage
In the polymers of amino acids, different amino acids are linked together through a bond or linkage, which is known as peptide bond or Peptide bond or Peptide Linkage.


When the hydrogen of amino acid combine with the OH group of other amino acid to form water, the bond between Nitrogen of one amino acid and carbon of other amino acid is formed which is known as Peptide Bond or Linkage. This peptide bond is formed in proteins which are the polymers of amino acids.

Diagram Coming Soon



Essential Amino Acids
Naturally occuring amino acids are known as, essential amino acids.

A large number of sunthetic amino acids are known, but only 20 amino acids occur in nature.




Properties of Amino Acids
The properties of amino acids are as follows.

1. Amino acids are soluble in water, but insoluble in organic solvents.

2. Amino acids are solids.

3. Amino acids have high melting point.

4. They donate or accept proton in the medium in which they are dissolved.




Function of Amino Acids
The role of amino acids in the human body is as follows.

1. Amino Acids can be synthesized back into Proteins.

2. Amino Acids oxidize to provide energy.

3. Amino Acids may be transformed into carbon hydrates or fats.