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Frederick Griffith
Frederick Griffith was a British scientist, who was trying to figure out the role of bacteria in making people sick. Griffith mixed malevolent, disease-causing bacteria into harmless bacteria, and found that the amalgamation of the two was fatal. Both on their own, however, should not have been fatal. Through this bizarre occurence, he postulated that there was some factor that was involved in the transformation"of harmless bacteria into disease-causing ones. -
Oswald Avery
Avery discovered that Deoxyribonucleic Acid (DNA) serves as a genetic material, and published a paper with his colleagues in 1944 explaining about how DNA is the transforming principle. He did so by repeating Griffith's experiment with heat-killed bacteria, thus his results were influenced by Griffith. He mixed enzymes into an extract of the bacteria, destroying different biomolecules, to determine what caused the transformation; in the end he discovered that it was in fact DNA. -
Erwin Chargaff
Chargaff discovered that the percentages of Guanine and Cytosine in DNA are almost identical, whereas the percentages of Adenine and Thymine were almost equal. He did this by measureing the four bases in many different organisms, and parts of organisms, such as yeast and beef spleen. He thus deduced laws that Adeneine is present at the same amoung as Thymine, and Guanine is present in the same amount as Cytosine, although he did not know why. -
Rosalind Frank
Rosalind Frank was a British scientist. She used a technique known as X-ray diffraction, aiming a powerful X-ray at DNA. She recorded the patterns of the scatterings of the X-ray, and found a general X-shaped pattern for the DNA. She greatly influenced the work of Crick and Watson in their discoveries. -
Alfred Hershey and Martha Chase
Alfred Hershey and Martha Chase were two American scientists. They studied viruses and bacteria, and conducted an experiment in order to determine that DNA was the chemical component of genes.They grew viruses in cultures of phosphorous-32 and sulfur-35, which were used as markers for protein and DNA. Phorphorous was present in DNA, but sulfur was not, and vice versa for protein. Because phosphorous was far more present, the two conlcuded that DNA made up genetic material. -
James Watson and Francis Crick
Francis Crick, a British scientist, and James Watson, an American scientist, discovered the shape of DNA to be of the double helix shape. Through various attempts at modeling the molecule, they stubled upon the X-ray pattern, which led them to the conclusion that the DNA is indeed organized in a double helix. This provided them with crucial information on its ability to carry information, its duplication, etc.
