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Frederick Miescher was the first to discover the existence of DNA. In 1869, Miescher secluded DNA from a cell, which he named “nuclein”, since he found it in the nucleus of the cell. He realized this new molecule had importance that was equal to a protein. He also realized that this molecule was an acid and had a lot of phosphorus compounds. Miescher made this discovery by performing experiments on the chemical composition of leukocytes.

Sources:

http://www.dnaftb.org/15/bio.html#:~:text=In%201869%2C%20Friedrich%20Miescher%20isolated,DNA%20as%20a%20distinct%20molecule.

https://www.nature.com/scitable/definition/nucleic-acid-274/#:~:text=Miescher%20named%20his%20discovery%20%22nuclein,as%20deoxyribonucleic%20acid%20(DNA).

http://www.dnaftb.org/15/bio.html#:~:text=In%201869%2C%20Friedrich%20Miescher%20isolated,DNA%20as%20a%20distinct%20molecule.

https://pubmed.ncbi.nlm.nih.gov/34523295/#:~:text=One%20hundred%20fifty%20years%20ago,weight%20and%20high%20phosphorus%20content.

https://safeswisscloud.com/en/blog/1869-friedrich-miescher-discovers-nucleic-acid/

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In 1928, Frederick Griffith performed an experiment on bacterium, which revealed that DNA was the molecule that carried genetic information. His experiment suggested that bacteria is able perform transformation, which is a process where genetic information is transferred. Frederick Griffith lysed an infected strain of bacteria, and filtered out all of the internal structures of the cell. He, then mixed it with regular bacteria. This allowed him to be able to observe that the regular bacteria, also became infected. Through a series of experiments with bacteria and viruses that infect bacteria, Griffith was able to understand that DNA could be transferred and replicated to other cells.

Sources:

https://byjus.com/biology/griffith-experiment-genetic-material/#:~:text=What%20was%20Griffith's%20experiment%20and,through%20a%20process%20called%20transformation.

https://www.britannica.com/biography/Frederick-Griffith

https://www.nature.com/scitable/topicpage/isolating-hereditary-material-frederick-griffith-oswald-avery-336/#:~:text=This%20breakthrough%20resulted%20from%20a,the%20properties%20of%20a%20cell.

https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/griffiths-experiment#:~:text=He%20lysed%20the%20virulent%20strain,extract%20that%20caused%20this%20conversion.

https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/griffiths-experiment

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In 1944, Oswald Avery, one of the first molecular biologists and a pioneer in immunochemistry, discovered the technicality of how traits are passed from parent to offspring, and he found out that deoxyribonucleic acid, otherwise known as DNA, was responsible for it. Avery undertook an experiment where he and his team secluded a strain of bacteria, then transformed DNA into another strain, giving the characteristics to the second strain of bacteria. Oswald Avery basically researched deeper into the Frederick Griffith experiment. He found of that something was transmitting between bacteria.

Sources:

https://profiles.nlm.nih.gov/spotlight/cc/feature/biographical-overview#:~:text=His%20research%20career%20culminated%20in,as%20most%20scientists%20had%20assumed.

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In 1950, Erwin Chargaff discovered that the nitrogenous bases, such as adenine, thymine, cytosine, and guanine, had equivalent ratios. He did this through using a paper chromatography - which is a process that separates the components of a mixture- that separated different chemical substances in DNA samples. This research allowed for more discoveries of DNA structure and its replication.

Sources:

https://study.com/learn/lesson/erwin-chargaff-experiments-discovery-what-did-chargaff-discover.html

https://www.famousscientists.org/erwin-chargaff/

https://dnalc.cshl.edu/view/16012-Erwin-Chargaff-1950.html

https://www.thermofisher.com/blog/ask-a-scientist/what-is-chromatography/

https://www.sutori.com/en/item/1950-erwin-chargaff-establishes-his-rules-later-named-chargaff-s-rules-this

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Maurice Wilkins was awarded the Nobel Prize in 1962 along with James Watson and Francis Crick for his contribution of the clarification of the double-helix structure of DNA. In 1950, Wilkins began using x-ray diffraction start studying nucleic acids and proteins. Before Rosalind Franklin joined the unit, he successfully isolated single fibers of DNA and gathered some research about the structure of nucleic acids. Wilkins used X-ray diffraction work to discover the first crystalline symmetrical patterns of deoxyribonucleic acid.

Sources:

https://www.whatisbiotechnology.org/index.php/people/summary/Wilkins#:~:text=In%201962%20Wilkins%20was%20awarded,crystalline%20symmetrical%20patterns%20of%20DNA.

https://www.nature.com/scitable/topicpage/maurice-wilkins-behind-the-scenes-of-dna-6540179/#:~:text=Wilkins%20began%20studying%20nucleic%20acids,ray%20crystallography%2C%20joined%20the%20unit.

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In 1953, Rosalind Franklin published Photo 51, - which was published through an X-ray crystallography experiment - which confirmed that the structure of DNA consisted of two strands, creating a double helix. He also discovered the density of DNA. This discovery was crucial to provide an explanation for how life and genes are passed down through generation.

Sources:

https://www.britannica.com/biography/Rosalind-Franklin

https://www.rosalindfranklin.edu/about/facts-figures/dr-rosalind-franklin/

https://embryo.asu.edu/pages/photograph-51-rosalind-franklin-1952

https://www.livescience.com/2912-photo-51-changed-world.html

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In 1952, Alfred Hershey and Martha Chase made a discovery that confirmed DNA as the carrier of genetic information. They discovered that DNA is transferred from bacteriophages to bacteria. They were able to separate phages into radioactive sulfuring-containing protein ghost and radioactive phosphorus-containing DNA. Bacteriophages are viruses that infect and duplicate within bacteria to archaea.

Sources:

https://www.ncbi.nlm.nih.gov/books/NBK493185/

https://www.nobelprize.org/prizes/medicine/1969/hershey/facts/

https://embryo.asu.edu/pages/hershey-chase-experiments-1952-alfred-hershey-and-martha-chase

https://study.com/learn/lesson/hershey-chase-experiment-discovery-results.html

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In 1953, Pauling suggested that DNA was nucleic acid strands coiled up together in an elaborate triple helix. Then, with more research and resources, James Watson and Francis Crick’s discovery of the double-helix was proven with Pauling’s research and the research of others. Linus Pauling’s idea emerged from the idea that proteins existed as helixes. He used X-ray diffraction to confirm the accuracy of his work.

Sources:

https://embryo.asu.edu/pages/proposed-structure-nucleic-acids-1953-linus-pauling-and-robert-brainard-corey

https://www.sas.upenn.edu/~upshaw/chemproject.pdf

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In 1953, James Watson and Francis Crick discovered that deoxyribonucleic acid (DNA) is a double-helix structure, their model of DNA winning the Nobel-Prize. They built their model through the research of scientists such as Rosalind Franklin, Marcie Wilkins, and James Pauling. Rosalind Frankin took “photo 51”, which demonstrated the double-helix structure of the molecule DNA. Watson and Crick used this photo discovered by Franklin to create their double-helix model of DNA. Their research was a major breakthrough in the understanding of DNA, genetics, heredity, and reproduction.

Sources:

https://profiles.nlm.nih.gov/spotlight/sc/feature/doublehelix#:~:text=The%20discovery%20in%201953%20of,control%20the%20chemical%20processes%20within.

https://www.whatisbiotechnology.org/index.php/people/summary/Wilkins#:~:text=In%201962%20Wilkins%20was%20awarded,crystalline%20symmetrical%20patterns%20of%20DNA.

https://www.famousscientists.org/linus-pauling/