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Miescher
Meischer identified “nuclein” (which was renamed nucleic acid and then DNA) inside the nuclei of human white blood cells.
He wanted to isoclate and characterize the protein components of white blood cells. He then came across a substance that wasn’t anything like the protein. He then realized he discovered a new substance.
This allowed people to understand that a substance existed in cells that could have varying components that were equivalent to proteins. -
Chargaff
Chargaff discovered that the nucleotide composition of DNA varies among species and no DNA maintains the same properties but the amount of pyrimidines and purines were almost equal (Chargaff’s rule).
He set out to see if there were differences in DNA among species.
His discovery allowed people to understand that pyrimidines and purines are usually equal despite the fact that everyone has a different DNA composition. -
Hershey & Chase
Hershey and Chase discovered that DNA is the genetic material of a cell.
While injecting radioactive bacteria into nonradioactive bacteria they realized that all the cells became radioactive because the DNA that was injected changed the traits of the cell.
This allowed people to understand the function of DNA -
Watson & Crick
Watson and Crick discovered that DNA exists in a double helix. They used cardboard cutouts and shifted molecules around like they were putting together a puzzle. They were trying to create a 3D model of DNA.
This helped people understand the basic shape of DNA. -
Franklin
Franklin discovered that there are two forms of DNA shown in her X-ray images (a dry “a” form and a wetter “b” form). Watson and Crick then used her X-rays to create their DNA model.
She wanted to refine her X-ray images using finer DNA fibers and arrange them differently using chromatography when she noticed a difference in the DNA.
Her X-rays led to the understanding of the double-helix shape of DNA but she wasn't given credit for her work with Watson and Crick. -
Meselson & Stahl
Meselson and Stahl discovered that DNA replicates in a semiconservative way where the DNA can proceed in a circular or linear fashion.
They tried to distinguish between old and new DNA so they replicated bacteria to determine if DNA replicated conservatively or dispersively.
This allowed people to understand that DNA replicates in a semiconservative method.
