The History of DNA
By: Marisa Attri
Gregor Mendel was a European monk who discovered many rules of heredity. His research and discovery about dominant and recessive traits lasted from 1856 to 1863. Mendel discovered through selective cross breeding that over time, certain characteristics would show up in offspring. He experimented with pea plants that had clear opposite characteristics. When he found that certain characteristics kept showing up, he concluded that there are dominant and recessive traits. Mendel furthered the study of genetics by pointing out different types of traits or genes, which makes up our DNA. He didn't necessarily come up with a part of the DNA structure, but he figured out that certain traits that come from our parents, make up living things.
Fredrick Griffith was a bacteriologist who performed an experiment involving pneumonia and mice in 1928. Griffith studied two strains of bacteria, and found that one could be changed into the other form. One strain caused pneumonia and one did not. When he mixed the two and injected the mouse, the mouse died. This proves that the non-pneumonina causing bacteria transformed into the pneumonia causing bacteria. When it transformed it absorbed genetic material from the other strand and then turned into that strand. This furthered genetics and contributed to the discovery of the structure because they could then infer that the genetic material was DNA.
Oswald Avery was a bacteriologist and research physician. In 1944, Oswald discovered that the molecule that transformed the strains in Griffiths experiment was DNA. This furthered genetics because this said that DNA was responsible for the transfer of genetic material. This contributed to the discovery of the structure because it told us that DNA somehow has to transfer genetic material.
Erwin Chargaff was a scientist who figured out the amounts of A, T, C, and G in species. In 1950 he found that the amount of A=T and C=G. This furthered genetics because it tells us which bases are equal and how the calculate any missing base. This contributed to the cell structure because it told people which letters fit together.
Rosalind Franklin was an awarded young lady who discovered phosphates in 1951. She discovered the basic dimensions of DNA strands and that phosphates were on the outside of a helical structure all from just looking at a detailed photo. This furthered genetics because it expanded our knowledge of DNA strands and phosphates. This contributed to the cell structure because it told us how big DNA probably was and that phosphates were on the outside. It also told us that it is in the shape of a double helix.
Maurice Wilkins was a scientist who basically discovered that DNA has a three dimensional helical nature in 1951. This contributes to genetics and the discovery of the structure because it told people that DNA was shaped like a twisted ladder.
James Watson and Frances Crick
James Watson and Frances Crick were in Cambridge, England and both determined to create an accurate model of DNA. In 1953 they were able to do just that, creating a model from x-ray data. The model included phosphates and hydrogen bonds, 2 holding thymine and adenine together and 3 holding cytosine and guanine together. This furthered genetics because it lets humans see what our DNA looks like and what it is made up of. This contributed to the discovery of the cell structure because it was an actual model of it.