BIOMOLECULES: INTRODUCTIION

 Numerous substances are produced by cells and living organisms are called biomolecules, often called Biological Molecules. Biomolecules may vary in size, structure and performs a wide array of functions. The four major types of biomolecule are carbohydrate, protein, lipids, and nucleic acid. Among biomolecules, nucleic acids are of two types DNA and  RNA, both have the unique function of storing an organism's genetic information- to be specific the sequence of nucleotides that determines the a/a sequence of a protein, which are of critical importance to life on Earth. There are 20 different amino acids that can occur within a protein; the order of arrangement of these amino acids decides the function and structure of the protein. Proteins play a major role as structural elements of a cell. Proteins present in the cell membrane are either intrinsic ( penetrates and binds tightly to the lipid bilayer ) or extrinsic( bound loosely bound to the polar surface).

They also serve as a transporter, moving nutrients and other molecules inside and outside of the cell, as well as an enzyme and catalyst for vast chemical reactions taking place inside a living organism. Proteins also form antibodies and hormones and they influence various gene activities. Likewise, carbohydrates, which are made up of molecules primarily containing carbon, hydrogen, and oxygen. It is an essential source of energy and a structural component of life. Carbohydrates are the most abundant biomolecule found on this Earth. Further classified into four categories on the basis of sugar units: Monosaccharides, disaccharides, oligosaccharides, and polysaccharides. 

Another key biomolecule of a living organism, Lipid. It serves as a source of stored energy and acts as a chemical messenger. Lipids form a membrane that separates the cell from the external environment as well as compartmentalizes the interior of the cell giving rise to cell organelles like mitochondria and nucleus. All biomolecules share in common a fundamental relationship between structure and function. Lipids, for example, are hydrophobic in water, while the hydrophilic ends are exposed to the water. This arrangement gives rise to the lipid bilayer or two layers of phospholipid molecules, which forms the membrane of cell and organelles. On the other hand, DNA which is around  2m long coiled tightly to get fit inside a nucleus of size 6 micrometer.DNA packaging into chromatin and chromosome wraps around a protein called histone form units are known as a nucleosome. These units condense further into chromatin fiber which condenses more to form a chromosome.