Proteins : The Building Blocks of Life


Proteins are known as the building blocks of life because they are the most abundant molecules present in the body and forms about 60% of the dry weight of cells. Apart from cells, most of the enzymes, regulatory and structural parts of the body are made up of proteins. As a result, they are essential for the growth and development of an individual. Food like eggs, pulses, milk and milk products form the major high protein foods for the body.

Protein structure comprises of long chains of amino acids. The amino acids structure and position gives particular properties to the proteins. Amino acids are made up of an amino functional group (-NH2) and  a carboxyl group (-COOH). Amino acids can be of various types, namely – α, β, γ, σ, etc.proteinsThere exists 20 naturally occurring amino acids which are further classified into essential and nonessential amino acids.

  • Essential amino acids are those which are not manufactured by the body and hence, have to be taken up from outside.
  • Non essential amino acids are manufactured inside the body and hence, need not be supplied from outside.

The amino acids are generally represented using three letters. They can also be represented using one letter for easier convention as given in the image below.

Single-Letter Amino Acid Code

Chemical Properties

The chemical properties of the amino acids are decided by their structure.For example, the acidity and the basicity is governed by the relative number of amino and carboxyl groups.

  • Higher the concentration of the carboxyl group, higher the acidity.
  • Higher concentration of amino group results in higher basicity.

However, the presence of both acidic and basic groups can result in the formation of Zwitterion which is in overall neutral in nature, in spite of having both positive and negative charge on the molecule.

These chemical properties and the structure of amino acids impart these physical properties like:

  • Water solubility
  • High melting point
  • Crystalline
  • Colourless
  • Salt like behavior

All these properties of amino acids decide the ultimate structure and function of proteins. The protein structure gives it its functionality.

We have thus discussed about proteins, their structure and amino acids in brief. Continue through the Byju’s app to study more about protein structure and more.

Practise This Question

The number of disulphide linkages present in insulin is 
(JEE Main, 2013)