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Hermann Muller
In 1920, Muller showed that x-rays could induce mutations. The significance of this discovery is that it creates a caution when taking the risk of getting an x-ray. -
Barbara McClintock
McClintock correlated chromosome behavior with results of breeding experiments in corn. This led to her discovery of translocations, inversions, deletions and ring chromosomes in corn. -
Oswald Avery
Avery did a series of experiments strains of pneumococcus bacteria, causing pneumonia. The significance is that the S- strain creates pneumonia and the R- strain doesn't. -
Evelyn Witkin
Witkin identified a strain of E. coli bacteria known a B/r that was more resistant to radiation than the parental B strain. The significance is that this was the first mutations conferring resistance to radiation had been isolated. -
Erwin Chargaff
Chargaff discovered that Levene's Tetranucleotide theory was incorrect because all organisms don't have the same DNA. The significance of this was that people now believed organisms don't have the same DNA as others. -
Rosalind Franklin
Franklin improved x-ray crystallography unit at king;s college in London. The significance is that deduced the basic dimensions of DNA strands, and that the phosphates were on the outside of what was probably a helical structure. -
Hershey- Chase
Hershey and Chase studied bacteriophage genetics. The significance is that they concluded that phage DNA alone carries the instructions needed to replicate phages inside the bacteria. DNA is the genetic material -
James Watson
came up with the structure of DNA. The significance is that now theres is a correct and proper structure for all DNA. -
Francis Crick
came up with the double delix structure for DNA. the significance is that the structure allows for the DNA to be tightly packed into chromosomes. it also provides an extremely stable backbone with the negatively charged phospates pointing to the outside of the molecule. this charge aids in the attachment of other molecules to the strand of DNA. -
Meselson-Stahl
The two showed that new DNA is made by copying from the old. The significance is that their experiment made clever use of nitrogen isotopes and "density gradient" centrifugation.
