Discovery of DNA

1. Discovery of DNA By Sonali Patel

2. Friedrich Miescher • 1869 was the starting point of DNA discovery. • Swiss Chemist Friedrich Miescher was the first to identify DNA as an important unique molecule. • Identified nuclein • Experimental process leading to the discovery of unknown chemical properties using pus. • Goal: Isolate and characterize proteins

3. Phoebus Levene • - Discovered DNA components of a single nucleotide which included: phosphates, sugars, bases as well as ribose. • - Identified how RNA and DNA are put together • - Levene’s Polynucleotide Model • - In 1919 proposed that nucleic acids were composed of nucleotides. • - Tetranucleotide structure • Nitrogenous bases: Adenine and guanine = Purines • Cytosine and Thymine = Pyridines.

4. Ervin Chargaff • - Biochemist that expanded on Levene’s work researching for additional details of DNA structure. • - Developed a new paper chromatography method • Difference between species • - A+T= C+T • - Chargaff’s research was the backbone for Watson and Crick

5. Rosalind Franklin • - Researcher at King’s College London in biophysics • - Well known for studying DNA • - Teamwork discovery with Raymond Gosling • - Photograph 51 • The dark spots at the top and bottom of the image represent DNA bases. • The dark spots making the cross indicate that there is a helical form. Photograph 51

6. Linus Pauling • - Discovered the structure of proteins • - Used origami to get a visual understanding of protein, amino acid layout • - His work contributed to Watson and Crick’s discovery

7. Watson and Crick • - The discovery of the double helix occurred in 1953 by Watson and Crick. • - Research indicates that DNA consists of two polynucleotide chains that are made of 4 nucleotide subunits. • - There are hydrogen bonds between the nucleotides holding the two chains together, and these nucleotides are composed of a 5 carbon sugar.

8. Nikolai Kolstov • - Russian Biologist father of modern genetics and pioneer of biotechnology • - Career as a Zoologist, studying the anatomy of vertebrates. • - First pioneer of the cytoskeleton • - Founder of the Institute of Experimental Biology in 1917

9. Frederick Griffith • Frederick Griffith was a British Bacteriologist that was looking to develop a vaccine that worked against pneumonia. • - Usage of 2 strains of Streptococcus pneumoniae bacteria and mice. • - R strain (rough) was known to be non-virulent bacteria. • - S strain (smooth) was known to be virulent bacteria • - Results showed that R-strain bacteria are able to transform to S bacteria from heat-killed S bacteria. Thus known as the Transforming Principle

10. Hereditary Components • - “It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material.” – Watson and Crick • - DNA encodes information through the order or sequence of the nucleotides along each strand. • - The genetic information stored in an organism’s DNA contains the instructions for all the proteins the organism will ever synthesize.

11. Works Cited • - Behind the picture: Photo 51, MRC: Medical Research Council, 25 Apr. 2013. • - Carr, Steven M. Watson and Crick Model of DNA, Memorial University, 2016. • - Cold Logic, Linus Pauling the Structure of Proteins, 2015. Accessed 9 Sept. 2019. • - O'Connor, C. (2008) Isolating hereditary material: Frederick Griffith, Oswald Avery, Alfred Hershey, and Martha Chase. Nature Education 1(1):105 • - Pray, L. (2008) Discovery of DNA structure and function: Watson and Crick. Nature Education 1(1):100 • - Rosalind Franklin Biography, Biography, 23 June 2019. • - The History of DNA Timeline, DNA Worldwide, 2014. • -Watson, James D., and Francis H. Crick. A Structure for Deoxyribose Nucleic Acid. Vol. 171, 1953, pp. 737-38.