DNA Timeline

Shairah Carpio Period 4 December 7 2012


Gregor Mendel

1863 - 1866

His study on pea plants lead to the laws of inheritance in which genes are known to be inherited by parents.

Thomas Hunt Morgan


His study on fruit flies led to the chromosomal theory of inheritance. He studied the genetics that underlie inheritance.

Frederick Griffith


His experiment concluded that protein was not the genetic material and hinted that DNA is the genetic material that caused the bacterial transformation.

Avery, McCarty and Macleod


Read Griffith's experiment and made an experiment with injected rough bacteria. The rats with digested proteins lived, while those of digested DNA didn't. Showed that DNA was the transforming material

Edwin Chargaff


Came up with the percentages of nucleotide bases. Showed that the number of A=T and C=G. This is consistent with the DNA structure Watson and Crick formulated because the purines are paired with pyrimidines

Linus Pauling


Came up with the triple-helix DNA model. This model motivated Watson and Crick to solve the real structure of the DNA before Pauling.

Hershey and Chase


By testing with radioactive protein and radioactive DNA, they found evidence that DNA alone is the hereditary material because DNA entered bacteria. Motivated Watson and Crick to study DNA structure

Maurice Wilkins


Helped Watson and Crick by showing them Photo 51, helping them determine that the DNA is a double helix.

Rosalind Franklin


Discovered the A and B forms of DNA. Used xray crystallography to determine the double helix structure of DNA. Her picture of DNA is what Watson and Crick used to modify their structural model.

Watson and Crick


Made the structure model of DNA. Helped future scientists study the DNA better.

Meselson and Stahl


Designed an experiment that led to the semiconservative replication model of DNA, disproving the conservative model. Shows that two original DNA strands separate and new complementary strands result