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Miescher
Miescher discovered "nuclein". He discovered nuclein by studying used bandaids that were contaminated with pus which contained high amounts of leukocytes that would be useful to identify the proteins in these cells. Instead of proteins, he discovered a different substance (nuclein). The discovery of nuclein, now referred to as deoxyribonucleic acid (DNA), has allowed scientists after Miescher to expound upon this discovery, whereas before there was no detail of a cell's DNA or structure. -
Chargaff
Chargaff discovered complementary base pairing. The four nitrogenous bases have one pair (A to T, G to C). He also found that purines must pair and be equal to pyrimidines. Lasty, the base amount varies in species but the same rule of the base ratios being equal remains. This was discovered by using paper chromatography, allowing him to know the base amounts in DNA. This discovery further clarified the structure of DNA because of the pairs of nitrogenous bases and the rules that proceed them. -
Hershey and Chase
Hershey & Chase discovered that the genetic material transferred from bacteriophages to bacterial cells is DNA. This was discovered by an experiment analyzing if the bacteriophage entered protein or DNA into the bacterial cell. This was done by growing viruses in cultures containing radioactive isotopes of phosphorus and sulfur. Radioactivity results showed phosphorus, proving the genetic material was DNA, not protein, providing that DNA is the genetic material found in all living cells genes. -
Franklin
Franklin made the discovery of phosphates residing on the outside of a potentially helical structured DNA. Also, she discovered the dimensions of the DNA strands. These discoveries were accomplished by her high resolution crystallography x-rays of DNA fibers. Because of her discoveries, we know there is a phosphate on the outside of the DNA molecule. Franklin's discovery of the dimensions and new components expanded the structure of DNA and led to the discovery of the DNA double helix model. -
Watson and Crick
Watson & Crick discovered the structure of the DNA molecule, which is a double helix molecule, complete with four different nitrogenous bases paired in twos. They discovered this with the help of Franklin's x-ray pictures and by constructing ball and stick models of their hypothesis of the structure of DNA. Because of their discovery, there is a clear picture of what a DNA molecule looks like, whereas before there was only bits of information as it was discovered pertaining to DNA structure. -
Meselson and Stahl
Meselson & Stahl discovered that DNA replicates in a semi conservative manner, meaning a DNA molecule is composed of one new strand and one original stand of DNA. They discovered this by an experiment in which they grew E.coli and eliminated all other forms of replication because of the densities in the DNA in each round of results. This solidified that DNA replicates semi conservatively, expanding upon the previous discoveries of DNA structure by discovering a pivotal function of DNA.
