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History of DNA

DNA is an important, if not critical substance in the maintenance and production of living organisms. Its crucial role in all living organisms goes without saying, and its appearance on the scientific blackboard is a relatively modern one, at best.


DNA was first discovered as an individual substance by a Swiss physician named Friedrich Miescher. In 1869, he discovered a microscopic substance in the remnants of old discarded surgical bandages. Referring to this substance originally as 'nuclein', because of its residence in the nuclei of the cell.

It was later discovered in 1919, by a scientist named Phoebus Levene, that this substance contained a base, sugar and phosphate unit make-up. It was also suggested by this same scientist, that the 'nuclein' substance maintained a 'string' of nucleotide units, linked together by phosphate connections. Furthermore, it was also thought that the 'chain' itself was short and that the bases repeated in short patterns.

An X-ray diffraction analysis in 1937 by William Astbury, revealed that DNA itself, had a regular structure. Further down the line, in 1928, a bacteriological study by a scientist of the name Frederick Griffith clearly illustrated the role of this new substance in the carrying of genetic information. DNA was further confirmed as a component of heredity when the Hershey-Chase experiment of 1952 isolated DNA as the genetic information base of a bacteriophage known as the T2 phage.

In 1953, a set of X-ray diffraction images (by Rosalind Franklin) conclusively illustrated the 'pairing' of base pairs, upon which scientists of the names Watson (James D.) and Crick (Francis) suggested what is commonly now accepted as the first accurate structural model of what we now know as DNA. Watson, Crick and Wilkins all shared a Nobel prize for their roles in the discovery, just shortly after the death of Franklin. Arguments are still ongoing as to whom exactly should have received credit for the prize.

James Watson Francis Crick
James D. Watson Francis Crick


In 1957, Crick finished developing a dogma of molecular biology, outlying the relationship between DNA, RNA and other proteins. He furthermore indicated that the genetic code itself was based on a series of non-overlapping 'triplets' of base pairs, typically referred to as codons. This work allowed scientists Khorana (Har Gobind), Holley (Robert W.) and Nirenberg (Marshall Warren) to decipher what is commonly now known as the genetic code.


History

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