DNA Timeline by Ananya Raja https://padlet.com/araja15/nunf5guqbryhkxi7 en-us 2023-02-02 17:51:19 UTC 2025-10-06 01:56:01 UTC hello@padlet.com https://padlet.net/icons/png/1f9ec.png Frederick Miescher (1869) araja15 https://padlet.com/araja15/nunf5guqbryhkxi7/wish/2466532755 Discovery -  He was a Swiss Biochemist working for Ernst Hoppe-Seyler at the University of Tübingen, and he discovered a substance that has phosphorus and nitrogen in the nuclei of a white blood cell. He also separated the parts of a certain part into its protein and acid components. The whole of this was called nuclein and then nucleic acid further into the future, this specific one was also called deoxyribonucleic acid.

Citation(s):
1) Britannica, T. Editors of Encyclopaedia.(2022, August 22) Friedrich Miescher. Encyclopedia Britannica. Retrieved February 3, 2023, from https://www.britannica.com/biography/Friedrich-Miescher.   
2) Safe Swiss Cloud. (2022, August 10). 1869: Friedrich Miescher discovers nucleic acid. Safe Swiss Cloud. Retrieved February 3, 2023, from https://safeswisscloud.com/en/blog/1869-friedrich-miescher-discovers-nucleic-acid/  ]]> 2023-02-02 17:51:19 UTC https://padlet.com/araja15/nunf5guqbryhkxi7/wish/2466532755 Frederick Griffith (1928) araja15 https://padlet.com/araja15/nunf5guqbryhkxi7/wish/2466532759 Discovery - He experimented with bacteria to discover that DNA carries all the genetic information in our bodies. His experiment used two strains of the bacteria called Streptococcus pneumonia. When Griffith inserted each strand into two mice, one mouse got infected and died, while the other wasn’t and remained “free.” (transforming principle)

Citation(s):
1) Britannica, T. Editors of Encyclopaedia (2023, January 1). Frederick Griffith. Encyclopedia Britannica. https://www.britannica.com/biography/Frederick-Griffith
2) Khan Academy. (n.d.). Classic experiments: DNA as the genetic material (article). Khan Academy. Retrieved February 2, 2023, from https://www.khanacademy.org/science/biology/dna-as-the-genetic-material/dna-discovery-and-structure/a/classic-experiments-dna-as-the-genetic-material ]]> 2023-02-02 17:51:19 UTC https://padlet.com/araja15/nunf5guqbryhkxi7/wish/2466532759 Oswald Avery (1944) araja15 https://padlet.com/araja15/nunf5guqbryhkxi7/wish/2466532762 Discovery - He was a Canadian-American bacteriologist that helped determine that DNA is responsible for heredity. He worked with his colleagues to disprove the common agreement among scientists that proteins are not responsible for hereditary information. DNA is responsible for it and serves as the cell’s genetic material.

Citation(s):
1) Britannica, T. Editors of Encyclopaedia (2022, October 17). Oswald Avery. Encyclopedia Britannica. https://www.britannica.com/biography/Oswald-Avery
2) Difference between DNA and protein (DNA vs protein). Major Differences. (n.d.). Retrieved February 2, 2023, from https://www.majordifferences.com/2018/01/difference-between-dna-and-protein-dna-vs-protein.html

]]> 2023-02-02 17:51:19 UTC https://padlet.com/araja15/nunf5guqbryhkxi7/wish/2466532762 Erwin Chargaff (1950) araja15 https://padlet.com/araja15/nunf5guqbryhkxi7/wish/2466532763 Discovery - Erwin Chargaff was one of the greatest known biochemists who had laid out the groundwork for one of the most significant discoveries of the 20th century for biology. He found that the four chemical bases in our DNA had occurred in pairs, which helped in finding a coding system of the hereditary material of all living organisms. He found all this when, whenever he looked at animal and plant tissue, there would always be around the same amounts of adenine and thymine and cytosine and guanine, and that adenine would always be paired with thymine and cytosine with guanine.

Citation(s):
1) Wright, P. (2002, July 2). Erwin Chargaff | Education | The Guardian. The Guardian. Retrieved February 5, 2023, from https://www.theguardian.com/news/2002/jul/02/guardianobituaries.obituaries  
2) Ebemidayo, F. (2021, September 3). The DNA structure model - A history of the double helix. Nebula. Retrieved February 4, 2023, from https://nebula.org/blog/dna-structure-model/  

]]> 2023-02-02 17:51:19 UTC https://padlet.com/araja15/nunf5guqbryhkxi7/wish/2466532763 Maurice Wilkins (1950) araja15 https://padlet.com/araja15/nunf5guqbryhkxi7/wish/2466532766 Discovery - He was a British biophysicist that won a Nobel Prize for his contribution to the x-ray diffraction image of DNA structure. He also brought the x-ray diffraction image Rosalind Franklin took to James Watson and Francis Crick and revised their publication of their model of the double helix of DNA.

Citation(s):
1) Britannica, T. Editors of Encyclopaedia (2022, December 11). Maurice Wilkins. Encyclopedia Britannica. https://www.britannica.com/biography/Maurice-Wilkins
2) Indigo Instruments. (n.d.). Retrieved February 2, 2023, from https://www.indigoinstruments.com/molecular_models/dna-rna/dna-double-helix-structure-model-17-base-pairs.html
3) Professor Maurice Wilkins. What is Biotechnology? (n.d.). Retrieved February 2, 2023, from https://www.whatisbiotechnology.org/index.php/people/summary/Wilkins 

]]> 2023-02-02 17:51:19 UTC https://padlet.com/araja15/nunf5guqbryhkxi7/wish/2466532766 Martha Chase and Alfred Hershey (1952) vkondapa https://padlet.com/araja15/nunf5guqbryhkxi7/wish/2466567215 Discovery - They were American Biologists, and the outcomes of their experiment supported Oswald Avery’s contribution to the discovery of DNA. Their experiment was to have two populations of bacteriophage particles, then label one population with a radioactive isotope (on the outer protein coat) and the other population’s DNA. Then, they allowed each population to attack bacteria and concluded that in bacteriophages’ (but we know this applies to every living organism), DNA has the hereditary material responsible for things such as the virus, not proteins.

Citation(s):
1) Molecular genetics. Britannica. (n.d.). Retrieved February 2, 2023, from https://www.britannica.com/science/heredity-genetics/Molecular-genetics#ref502866
2) Wikimedia Foundation. (2023, January 10). Hershey–Chase experiment. Wikipedia. Retrieved February 2, 2023, from https://en.wikipedia.org/wiki/Hershey%E2%80%93Chase_experiment ]]> 2023-02-02 18:13:59 UTC https://padlet.com/araja15/nunf5guqbryhkxi7/wish/2466567215 Linus Pauling (1952) araja15 https://padlet.com/araja15/nunf5guqbryhkxi7/wish/2466567267 Discovery - He was an American Scientist who worked with Robert Corey (protein crystallographer) to propose a three-chain helical structure for DNA. This was later proved wrong by James Watson and Francis Crick, who said that DNA is a double helix instead of three. (thought the phosphates were on the inside and the nitrogens were on the outside)

Citation(s):
1) National Institutes of Health. (n.d.). The search for the molecular helix . U.S. National Library of Medicine. Retrieved February 4, 2023, from https://profiles.nlm.nih.gov/spotlight/mm/feature/biomolecules
2) Paradowski, R. J. (2023, January 24). Linus Pauling. Encyclopedia Britannica. https://www.britannica.com/biography/Linus-Pauling
3) Wikimedia Foundation. (2022, September 16). Triple-stranded DNA. Wikipedia. Retrieved February 4, 2023, from https://en.wikipedia.org/wiki/Triple-stranded_DNA ]]> 2023-02-02 18:14:02 UTC https://padlet.com/araja15/nunf5guqbryhkxi7/wish/2466567267 Rosalind Franklin (1953) vkondapa https://padlet.com/araja15/nunf5guqbryhkxi7/wish/2466568687 Discovery - She was a British scientist who was most known for her discovery of the molecular structure of DNA as a double- helix polymer. She used x-ray diffraction to study DNA when she joined the Biophysical Laboratory at King’s college. Here she discovered the chemical structure and also the density of DNA. She used x-ray diffraction to get clearer images of the patterns of the molecules. She was the one who had laid the foundation for James Watson and Francis Crick’s model for DNA. (photo 51)

Citation(s):
1) Britannica, T. Editors of Encyclopaedia (2022, November 18). Rosalind Franklin. Encyclopedia Britannica. Retrieved February 4, 2023, from 
https://www.britannica.com/biography/Rosalind-Franklin
2) Walsh, F. (2012, May 16). The most important photo ever taken? BBC News. Retrieved February 4, 2023, from https://www.bbc.com/news/health-18041884 

]]> 2023-02-02 18:15:07 UTC https://padlet.com/araja15/nunf5guqbryhkxi7/wish/2466568687 James Watson and Francis Crick (1953) vkondapa https://padlet.com/araja15/nunf5guqbryhkxi7/wish/2466569649 Discovery - They were both British scientists working for Cambridge University and were two of the many scientists working to figure out the structure of DNA. They built a model of the structure of DNA, which was a double-helix polymer, and they also found out that DNA replicated by separating into individual strands, which both become the template for a new double helix. A book had been written by Watson called “The Double Helix,” which had explained their discovery. There was a controversy that had risen over Watson and Crick for using the work of another scientist, and this was because they had used Rosalind Franklin's research and photographs for their discovery, and they had not included her in the Nobel Prize they won. 

Citation(s):
1) History.com Editors. (2021, March 2). Chemical structure of DNA discovered - history. HISTORY. Retrieved February 4, 2023, from https://www.history.com/this-day-in - history/watson-and-crick-discover-chemical-structure-of-dna
2) Pray, L. (2008). Discovery of DNA Structure and Function: Watson and Crick. Nature news. Retrieved February 5, 2023, from https://www.nature.com/scitable/topicpage/discovery-of-dna-structure-and-function-watson-397/ 
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