Scientists of DNA

Miescher

Jan 18, 1869

year: 1869
contribution: isolated "nuclein," DNA with proteins, from cell nuclei.
how: he was researching the composition of lymphoid cells — white blood cells. To do this he collected bandages from a nearby clinic and washed off the pus. He experimented and isolated nuclein
what did this add to knowledge of DNA: He was the first to identify DNA as a distinct molecule

Chargaff

Jan 18, 1949

year: 1949
what was contributed: he found that in DNA the amount of T was equal to A, and the amount of C was equal to G. This became known as Chargaff's Rule.
how: he did experiments in which he isolated the DNA, separated the purines and the pyrimidines,exposed the separate components of the solution to ultraviolet light which allowed him to see how much of each bases are in DNA.
how did this add to current understanding on DNA: his discovery helped the double helix be discovered

Franklin

Jan 18, 1951

year:1951
contribution: "photograph 51" which showed that the helical structure of DNA
found by: used the X-ray crystallography unit at King's College and found high-resolution photos of crystallized DNA fibers
how did this contribute to the understanding of DNA: her picture helped Watson and Crick confirm that the DNA structure is a double helix

Hershey & Chase

Jan 18, 1952

year: 1952
what they discovered: found that DNA is transferred from bacteriophages to bacteria. This confirmed DNA as the bearer of genetic information.
how: they used chemical tracers that resembled proteins and DNA. Then tracked their reproduction. From these experiments they concluded that DNA is associated with genetic material
what did this contribute of DNA: helped prove that proteins don't carry genetic information; DNA does

Watson & Crick

Jan 18, 1953

year of discovery: 1953
what they discovered: DNA molecule are in the form of a three-dimensional double helix.
how: crick was working on X-ray diffraction of proteins before he met Watson who stayed and helped him find that the DNA molecule has a double helix by using available X-ray data and the advancement model building
how did this add to current understanding on DNA: confirmed the structure of DNA

Meselson & Stahl

Jan 18, 1954

year:1954
what did they discover: that DNA is replicated semi-conservatively (half new dna and half old dna)
how:experiments on DNA replication using E. coli bacteria as a model system. they cut small pieces and then measured the density of the DNA using density gradient centrifugation.
how did this contribute to the knowledge of DNA: helped explain the process of DNA replication