HISTORY OF DNA

BY TAYLOR COURTNEY

We haven't always known what DNA is. Or that it even existed.


Below are some important scientists that made remarkable discoveries about DNA and its structure.

Gregor Mendel

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Gregor Mendel was a monk who lived in Central Europe. He did some basic research on genes and taught at a high school briefly, but he was not anything special. Yet. In 1866, his ideas were published, but they were not recognized until 1900. Mendel had undergone a series of experiments involving pea plants, and had made some shocking discoveries about heredity and genetics.


In his experiments, Mendel uncovered two policies, which turned out to be some of the most foundational policies of biology.

1. The Law of Segregation

Dominant and recessive traits are passed randomly from parent to offspring.

2. The Law of Independent Assortment

Traits are passed on independently from other traits.
These became known as Mendel's Laws.


A group of botanists conducted the same experiment and found that his results were originally published in 1866. They gave Mendel the credit for the discovery.


Many scientists disagreed with Mendel's ideas completely, but he is still widely recognized as the "father of modern genetics."

Fredrick Griffith

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Fredrick Griffith was a British bacteriologist. In 1928, he conducted Griffith's experiment, which was one of the first to prove that bacteria can pass on genetic information by a process called transformation.


In his experiment, he used mice and two strains of pneumonia. One of the dangerous strains was killed, but it transferred its DNA into the other non-infectious strain, infecting it and proving Griffith's theory or transformation. At this time, Griffith did not know what caused the change.


Griffith's experiment also allowed other scientists to realize that DNA (and not protein) was the molecule that held information.

Oswald Avery

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Oswald Avery was a Canadian bacteriologist and research physician. In 1944, he worked with two other scientists to further prove Griffith's theory. They used the same experiment and came to the conclusion that a widespread molecule called DNA caused this genetic transformation.


Avery's work allowed other scientists to further study the structure of DNA.


In 1945, Avery was awarded the Copley Medal for work in microbiology and, more importantly, his remarkable discovery that explained so much for the scientific world.

Erwin Chargaff

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Erwin Chargaff was an American biochemist and author.


Four bases make up the DNA molecule. In 1950, he published a piece that said in any living species, the ratio of adenine to thymine and cytosine to guanine within these bases had to be equal. These became known as Chargaff's ratios. They work for any living thing; the only difference is the number of C-G pairs and A-T pairs.


The discovery was also made that C could only pair with G, and T can only pair with A. Therefore, C is the complementary base pair for G, and vice versa.


This clue significantly helped the science community understand the structure of DNA.

Rosalind Franklin

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Rosalind Franklin was a British chemist and crystallographer. Franklin took many pictures of DNA through x-ray diffraction. These pictures and her various pieces of written notes helped Crick and Watson later uncover more about DNA.


Rosalind worked with Maurice Wilkins, a fellow scientist, for a time. She also worked with a student, Raymond Gosling, and captured two pictures of DNA, concluding that what she saw was probably a helix and that the phosphate were outside of the main structure.


In 1953, both Franklin and Wilkins simultaneously published pieces on the x-ray data, not knowing that the other was doing so as well.

Maurice Wilkins

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Maurice Wilkins was born in 1916 in New Zealand. In 1946, eight years after earning his degree, he began studying how to study nucleic acids with microscopes. Wilkins began with studying tobacco mosaic virus and the components inside. Later, he looked at x-ray diffraction pictures of DNA. The patterns that he noticed led to the discovery of the structure of DNA.


Later, further studies proved the Watson-Crick theory of DNA structure to be true.


In 1960, he was awarded the Albert Lasker Award by the American Public Health Association, along with Watson and Crick.

James Watson

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James Watson was born in Chicago and became a zoologist. After two degrees in zoology, Watson met Maurice Wilkins and decided to switch the focus of his studies in 1951. He was shown the x-ray diffraction pictures of DNA, and decided to focus on the chemistry of nucleic acids and proteins.


After meeting Crick and after one failed attempt in guessing the structure of DNA in 1951, Watson and Crick concluded the structure of DNA, a double helix, in 1953.


Along with Crick and many other awards, Watson was awarded the Research Corporation Prize in 1962.

Francis Crick

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Francis Crick was born in England in 1916. In 1951, Crick met James Watson, and began further researching the structure of DNA. They concluded the double helix structure in 1953, along with the replication scheme. This discovery of the structure of DNA explained other phenomenons and processes and provides a foundation for further research on DNA.


In 1954, Crick earned a PhD in physics, after having previously postponed it due to war.


In more recent years, Crick has done research on protein synthesis, the genetic code, and mutation with S. Brenner.

Conclusion

The road to discovering DNA and its structure has been long and hard, and without these scientists, information on these structures would still be unknown.