DNA History- Everything You Need To Know
DNA history spans over a 150 year period. It starts in the mid eighteen hundreds and continues up to the present 21st century. Today a lot of information of DNA exists. In the study of DNA history, we know what it is made of, how it replicates and many methods and tools have been developed to manipulate it for human uses.
DNA History in the Mid Eighteen Hundreds
DNA history started in the eighteen hundreds, before this there was no information on inheritance of characteristics and how it occurred. A scientist Gregor Mendel who was a monk by profession and trained in mathematics started experiments on the pea plant in the mid eighteen hundreds. Over a span of 8 years, he conducted multiple experiments which gave an understanding of what a trait is and how it is inherited from one generation to the other, thus the beginning of DNA history.
While the importance of his research was not realized in that as century DNA history per se, due to political reasons, in the nineteenth hundreds many years after he had passed away, his research was accepted and its importance realized. Today he is considered as the “Father of Genetics” for his research which has shaped the idea of inheritance and hereditary.
During the same time period another scientist managed to isolate DNA for the first time. But it was only isolated, there was no information on its use or its importance to life in general.
DNA History in the early Nineteen Hundreds
In a span of one hundred years, from 1900-2000, most of the information which we currently know was discovered, deciphered and perfected. DNA history in the early nineteen hundreds starts with:
- Frederick Griffith: In 1928, as a young army medical officer, he tried to find the cure for pneumonia. While he never discovered the cure for pneumonia, he did discover that a compound or molecule was present which allowed for the transfer of virulence from a virulent pneumonia bacterium to a non-virulent pneumonia bacterium. He conducted the following four experiments:
- In the first experiment, he injected a mouse with a virulent type of pneumonia bacteria (strain S), in this experiment the mouse died.
- In his second experiment, he injected a mouse with a non virulent type of pneumonia bacteria (strain R), in this experiment the mouse lived
- In his third experiment he injected a mouse with a heat killed virulent type of pneumonia bacteria (strain S), here the mouse lived.
- Finally in his last experiment, he injected a mouse with a heat killed virulent strain S pneumonia bacteria and also injected a strain R non-virulent pneumonia bacteria. Here he observed that the mouse died. These were the marks of DNA history.
DNA History Continued
- Erwin Chargaff: In 1940, he gave the Chargaff rule based on the following observation. He observed that of the four bases present in DNA (adenine, guanine, cytosine and thymine) the concentration of adenine was always equal to thymine and similarly the concentration of guanine was always equal to cytosine. The Chargaff rule states that
- The amount of Adenine will always equal Thymine &
- The amount of Guanine will always equal Cytosine
- Oswald Avery: In the year 1944, Avery who was interested in the Griffith experiment, conducted an experiment of his own on the pneumonia bacteria. He first took different vials of pneumonia bacteria and killed them. Then in each vial he selectively destroyed one component of the cell. In one he destroyed the carbohydrates, in one he destroyed the proteins in one he destroyed the lipids and finally in one he destroyed the DNA. When he added these mixtures to non-virulent bacteria, he observed that in the mixture where the DNA was destroyed, hereditary transformation or transfer of virulence did not occur. Thus he disproved a common misconception of that time period i.e. proteins were responsible for transfer of genes and hereditary. For the first time in DNA history it was proved that DNA was the genetic material. But, DNA history continued to evolve.
DNA History in the Mid-Nineteen Hundreds
In the short span of fifty years, the structure of DNA, how it replicates and many methods to manipulate the compound were identified. A paradox beginning of DNA history. It started with:
* Rosalind Franklin & Maurice Wilkins: In 1951 these scientists are credited with obtaining the first quality x-ray diffraction pattern of the DNA. Till that time, the structure of DNA was not known and a good pattern did not exist. They succeeded in their venture and managed to obtain a good pattern.
* James Watson & Francis Crick: These two are credited with finding the structure of DNA. When they viewed the x-ray pattern obtained by the above two scientists, they had an eureka moment and hypothesized that the DNA was a double helix, where two separate fragments were coiled around each other thus giving the ladder like, staircase like pattern observed in the x-ray diffraction pattern.
This is the DNA history, in the late nineteen hundreds information on the replication of DNA and techniques to manipulate were found. DNA history has grown much through out the years.
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