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## Events and researchers involved in the discovery of DNA (Deoxyribonucleic Acid) - 1830 - Proteins were thought to be the most important molecule (proteios (Greek) "of first importance") - late 1860 - Friedrich Miescher while characterizing proteins from pus cells a molecule different from protei...

## Events and researchers involved in the discovery of DNA (Deoxyribonucleic Acid) - 1830 - Proteins were thought to be the most important molecule (proteios (Greek) "of first importance") - late 1860 - Friedrich Miescher while characterizing proteins from pus cells a molecule different from protein was isolated from the nucleus and called it DNA. He also reported that the empirical formula of salmon sperm DNA is $C_{29}H_{49}N_9P_3O_{22}$. - 1866 - Ernst Haeckel discovered that the most obvious cellular component of a cell was the nucleus. - Edmund Wilson - using staining technique, he observed that the most important nuclear element handed from cell to cell was the DNA - 1928 - Frederick Griffith (US Medical Officer) did a transformation experiment using *Streptococcus pneumoniae* and declared the presence of transforming principle. The avirulent (R) strain was transformed into virulent (S) type. - 1944 - Oswald Avery, Colin Macleod and Maclyn McCarty identified that the transforming principle (TP) was DNA. When the DNA was treated with proteinases and Rnases, its transforming ability is retained but when treated with Dnases, transforming ability is lost. When TP was treated to remove proteins and RNA, the composition of the substance left matched the composition of the DNA - 1952 - Alfred Hershey and Martha Chase - using a blender experiment, they proved that DNA is the genetic material of bacterial viruses which is injected into the cell during infection. The DNA labelled with $P^{32}$ is injected into the cell while the labelled protein coat with $S^{35}$ remained outside. - 1952 - Norton Zinder, Joshua and Esther Lederberg using a transduction experiment in *Salmonella typhimurium* further proved that DNA is the genetic material. When bacteriophage infects bacterial cell, a transducing phage picks a gene, infects and integrates the gene into a recipient cell. - 1953 - The structure of DNA was discovered by Rosalind Franklin, Maurice Wilkins, James D. Watson and Francis C. Crick - Francis C. Crick - Ph. D. in Biophysics and started to work on x-ray studies of proteins at Cambridge Univ. in 1947. - James D. Watson - Ph. D. in Microbiology from Univ. of Indiana and in (1951) moved to Cambridge Univ. and shared office with Crick. - Maurice Wilkins - Ph. D. in Physics worked on radar and Manhattan Project and assistant Director of Medical Research at Kings College, London. He worked on