Most of us are familiar with the term DNA because this term is used in comics, genetic testsand sci-fi movies. DNA is a very famous term, a few things of which are known to common man.But some misconceptions are also there related to DNA.
What is DNA?
DNA stands for deoxyribonucleic acid. It is a molecule whichconsists of the code of an entire organism. It is the DNA which defines the structure,development,purpose and function of an organism. DNA is present in all the cells of aliving organism which is copied from the parent cells to the child cells.
DNA can be consideredsimilar to a program of a computer while the body of a cell can be consideredas hardware which the program is executedon. The cell continuously gets instructions from the DNA to carry outdifferent functionsall through its life.
DNA is very thin and is a very long molecule. It has a double helix ladder shape. We can divide the structure of DNA into two parts; the backbones and the bases. Backbones are the twisted pair structures located at the sides of the double helix shape. Backbones are responsible for holding the bases of DNA together. On the other hand, bases are the actual fundamental blocks and form the DNA code.
Four lettersrepresentthe bases; A, T, C and G. In fact, these four letters represent the nucleotides:adenine, thymine, cytosine and guanine. Between backbones,these nucleotides are connected in such a manner that only two particular nucleotides can connect together forming a pair: Nucleotide A will connect to only nucleotide T, and nucleotide C will connect to only nucleotide G.
The molecule of DNA cannot be fit into a cell without a packagingbecause it is very long. There are structures in cells to pack large molecules of DNA in a cell.Thesestructures are called chromosomes. Chromosomes are the coiled molecules of DNAwhich are tightly packed.One chromosome is composed ofa single DNA molecule. There are 23 pairs of chromosomes in the cells of the human body, which are located in the nucleus of each cell.
Genes are the sets of instructions in each string of DNA. The genes can be considered as the language which cells can understand. It is the genes which instruct the cells about making specific none These specific proteins are responsible for the survival, growth and functionality of a cell.
Threebillion bases are there in human DNA, and 99.9% of these bases are identical in all the people on earth It is only 0.1% of the bases that makes a human being different from other human beings.
In 1953,James Watson and Francis Crick discovered the double helix ladder shape of DNA.
In 1869,Friedrich Meischerfirst isolated the DNA from a cell.