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Amino Acids


Amino Acids





Writer�s view about Amino Acid.
                                                  Consider a universe. In which there are a number of planets. In these planets consider the earth. In the earth are many countries and in countries are cities and in cities are many buildings. When we consider a single building we come to know that it is made up of many bricks that are the basic building block.

Now let us imply this to human body. Our body is composed of many chemical substances. But we are only interested in proteins.

Proteins consist of many protein fibers that are �the countries of earth�. The protein fibers in turn consist of many polypeptide chains. A single polypeptide is made of groups of building blocks. When a group of those building blocks is examined it is revealed that each of them has a basic unit that is the AMINO ACID. Amino acid is the� brick�, basic structural entity for proteins.

Importance of amino acids.
                                        Amino acids help in performing the very vital functions of body like carrying oxygen (as hemoglobin), protecting the body (as antibodies) etc.

Occurrence and introduction.
                                               Up till now about 500 amino acids have been found out of which 170 are present in body cells.
But only 20-26 are required by humans. Out of those 20 amino acids, 10 are prepared by the body itself but called non-essential amino acids (Ghar ki murghii daal brabar XD).
Our body requires the ones which are not synthesized by it, hence essential amino acids and as the name says it all �essential�, without them body can face many diseases.

Structure.
                 These belong to the organic class of compounds with a central carbon atom to which is attached a ----COOH (carboxyl group), a ----NH2 (amino group) , a hydrogen atom and a R-group. This R may be any maaja gaama from the organic family or hydrogen in a single case this would be explained later in the topic.

For the time being let�s understand the concept ofacidic and basic amino acids.
This depends upon the two main functional groups attached to the carbon i.e. the amino group and carboxyl group.
When two NH2---- groups are attached to the central carbon atom then it is called basic amino acid.
When two COOH----groups are attached to the central carbon atom then it is called acidic amino acid.

*Reason*
                Amino group resembles ammonium which is a base, two such groups increase the pKa value and nitrogen tends to accept proton, making it a base.
Similarly carboxyl groups resemble carboxylic acids, which are acidic in nature. This lowers the pKa value and proton is removed.

Zwitter ion:
                   Now when a neutral  amino acid is subjected to a system of varied pH , certain changes occur in them.

FOR EXAMPLE:-                   
When a neutral amino acid is subjected to a system having lower pKa value the proton from amino group is transferred to the carboxyl group of the same amino acid i.e. within the same molecule. This gives a positive charge to the amino group and a negative charge on carboxyl group. On the whole there is no net electrical charge on the molecule. This is called zwitter ion or internal salt.

NOTE: on the basis of position of amino group attached to the central/alpha carbon we can name the amino acids as a-�-? amino acids.


Entry # 9 
By Ahmad Azeem

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