Biomoleculas

Biomolecules
Although there is vast diversity of living organisms. The chemical compositon and metabolic reactions of the organisms appear to be similar. The composition of living tissues and non-living matter also appear to be similar in qualitative analysis
.Closer analysis reveals that the relative abundance of carbon, hydrogen and oxygen is higher in living system.

All forms of life arecomposed of biomolecules only. Biomolecules are organic molecules especially macromolecules like carbohydrates, proteins in living organisms. All living forms bacteria, algae, plant and animals are made of similar macromolecules that are responsible for life. All the carbon compounds we get from living tissues can be called biomolecules.
 
Biomolecules Definition


Biomolecules are molecules thatoccur naturally in living organisms. Biomolecules include macromolecules like proteins, carbohydrates, lipids and nucleic acids. It also includes small molecules like primary and secondary metabolites and natural products. Biomolecules consists mainly of carbon and hydrogen with nitrogen, oxygen, sulphur, and phosphorus. Biomolecules are very large molecules of many atoms, that are covalently boundtogether.
Classes of Biomolecules
There are four major classes of biomolecules: 
Carbohydrates
Lipids
Proteins
Nucleic acids

Carbohydrates
Carbohydrates are good source of energy. Carbohydrates (polysaccharides) are long chains of sugars. Monosaccharides are simple sugars that are composed of 3-7 carbon atoms. They have a free aldehyde or ketone group, which acts as reducing agents and are knownas reducing sugars. Disaccharides are made of  two monosaccharides. The bonds shared between two monosaccharides is the glycosidic bonds. Monosaccharides and disaccharides are sweet, crystalline and water soluble substances.Polysaccharides are polymers of monosaccharides. They are unsweet, and complex carbohydrates.They are insoluble in water and are not in crystalline form. 

Example: glucose,fructose, sucrose, maltose, starch, cellulose etc.


Lipids

Lipids are composed of long hydrocarbon chains. Lipid molecules hold a large amount of energy and are energy storage molecules. Lipids are generally esters of fatty acids and are building blocks of biological membranes. Most of the lipids have a polar head and non-polar tail. Fatty acids can be unsaturated and saturated fatty acids. Lipids present in biological membranes are of three classes based on the type of hydrophilic head present:
. Glycolipids are lipids whose head contains oligosaccharides with 1-15 saccharide residues.  
Phospholipids contain a positively charged head which are linked to the negatively charged phosphate groups. 
Sterols, whose head contain a steroid ring.

Proteins

Proteins are heteropolymers of stingsof amino acids. Amino acids are joined together by the peptide bond which is formed in between the carboxyl group and amino group of successive amino acids. Proteins are formed from 20 different amino acids, depending on the number of amino acids and the sequence of amino acids. 

There are four levels of protein structure:
Primary structure of Protein - Here protein exist as long chain of aminoacids arranged in a particular sequence. They are non-functional proteins.
Secondary structure of protein - The long chain of proteins are folded and arranged in a helix shape, where the amino acids interact by the formation of hydrogen bonds. This structure is called the pleated sheet.
Tertiary structure of protein - Long polypeptide chains become more stabilizes by folding and coiling, by theformation of ionic or hydrophobic bonds or disulphide bridges, this results in the tertiary structure of protein.
Quaternary  structure of protein - When a protein is an assembly of more than one polypeptide or subunits of its own, this is said to be the quaternary structure of protein. Example: Haemoglobin, insulin. 



Nucleic Acids
Nucleic acids are organic compounds with heterocyclic rings....