Most of the people think that American biologists James Watson and English physicist Francis Crick discovered DNA in 1950. But the DNA was first discovered in the late 1860’s by the Swedish chemist Friedrich Miescher.
After the discovery by Swedish chemist, many other scientists such as Phoebus Levene and Erwin Chargaff did many discoveries in series that helps in the discovery of many other new things about DNA which later on get combined with one another. Watson and Crick may never reach their conclusion that DNA exists in 3-dimensional double helix structure.
First piece of the puzzle: DNA discovered by Miescher
Although very less people realize it, in 1869 Swiss chemist Friedrich Miescher firstly identified a substance known as “nuclein” which is present in the nucleus of human being in white blood cells. The term nuclein, later on, turned into nucleic acid and then to deoxyribonucleic acid (DNA). His plan was to singulate and characterizes not the nuclein but the protein components of white blood cells. After Miescher gets to know that he made an important finding, he wrote that “It seems probable to me that a complete family of such slightly varying phosphorous containing substance will appear, as a group of nucleins, that is equivalent to proteins”.
After 50 years of the discovery of Miescher, it was then broadly appreciated by the scientific community. In 1971, at the summit of the history of nucleic acid research, Erwin Chargaff stated that in a 19th-century science, the name of Charles Darwin was mentioned 31 times. And the name of Thomas Huxley was mentioned 14 times but there was no mention of Miescher’s name. The discovery by Miescher was very amazing among all the discoveries of 4 major cellular components (i.e. proteins, lipids, polysaccharides and the nucleic acids) in that date.
Later on, some scientists made some little changes to the Watson and Crick model of DNA, since its inception in 1953, there are four main features of this DNA model:-
- DNA is double chained helix, and the two chains are connected with each other through hydrogen bond.
- Most of the DNA helices are right handed, that means if we hold our right hand with the thumb pointed upside and fingers curled around the thumb. Then our thumb will represent the axis of the helix and fingers will represent sugar and phosphate backbone.
- DNA helix is anti parallel, that means that 5th end of one chain is paired with 3rd end of another chain. Phosphate group attaches nucleotides to each other.
- Not only hydrogen bonds are found between DNA bases, but the outer borders of nitrogen containing bases are also exposed and also available for hydrogen bonding also. Such hydrogen bonds provide an easy way to DNA for different molecules also which includes proteins that play important role in the replication and expression of DNA.