1950 James Watson & Francis Crick took up the quest of determining the three- dimensional structure of DNA, they believed that the DNA structure would be great importance. Watson and Crick accomplishment was in some measure built on the work of their contemporary DNA researchers. 1951 Rosalind Franklin x-ray crystallography of the DNA molecule without her know- ledge, for instance, was a vital step toward discovery. She began to capture pictures of DNA using x-ray diffraction.
She also pre- sented her findings in a talk and suggested hat the phosphate groups were on the outside of the molecule. 1953 James Watson and Francis Crick deliv- ered the structure of a double helix DNA molecule. They succeeded in connec- ting pieces, old and new, from friends to foe. 1926 Erwin Schrodinger had introduced an Equation that describe the behavior of matter. He proclaimed that living and non-living matter all obey the same laws as physics and chemistry, and proposed that living organisms should be treated in terms of molecular and atomic structure. 865 Gregor Mendel discovered the basic laws of heredity, and first used the word “gene. ” He deuced that genes come in pairs and are inherited as distinct units, one from each parent. He also tracked the segregation of parental genes and their appearance in the offspring of dominant or reces- Sive trait. 1869 Friedrich Miescher found substance in pus-soaked bandages, rich in white blo- od cells. He learned that the only source for nuclein was chromosomes, which he realized was a significant discovery.
He supported the “chemical heredity theory,” hich contends that our basic biological information is passed from generation to generation and is stored in chemical sub- stances in our cells. 1902 Archibald Garrod hypothesized that it was a gene mutation caused the inherited disor- der alkaptonuria, that the disease was un- born. He went on to study other diseases that were not genetic, not bacterial. The research continued to build up upon the idea that hereditary genetic material within the cell was important. 928 Frederick Griffith studied two different trains of pneumococci, the S-form and R-form. The S-form killed infected mice, while the R-form had no effect. He found living S bacteria in their dead bodies. He concluded that something had been trans- ferred between the two types of bacteria. Thomas Hunt Morgan wrote the Theory ofa Gene. He localized genes to specific locations on chromosomes. He also concl- uded that the genes were the hereditary unit Mendel had described as Chromosome Theory of Heredity.
His specific mapping of Genes onto chromosomes made biology ccessible for experiments. 1949 Erwin Chargaff studied the makeup of the DNA molecule, he discovered that the Structure was composed of a sugar, a phos- phate group, and four nitrogenous bases (ATCG). He isolated DNA from different organisms and measured the levels of each of the four nitrogenous bases. 1944 Oswald Avery showed that Fred Griffith’s “transforming principle” had been contamin- ated by proteins. He and his colleagues showed that proteases, enzymes that degrade proteins, had no effect on the heat-treated S pneumonia.