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Miescher's Discovery
Miescher's discovery improved upon our current understanding of DNA by it being the first to identify DNA as a unique molecule. The substance which he named "nuclein" would later be known as nucleic acid. Although Miescher did not understand the importance of DNA at the time, his discovery would lead future scientists such as Watson & Crick to explore DNA as the carrier of our genes. -
Miescher's Contribution
The first contribution to the structure of DNA was made by a scientist named Johann Friedrich Miescher. Miescher is known for the isolation and discovery of DNA. In 1869 at the University of Tübingen, Miescher examined the white blood cells inside of pus covered bandages collected from the local hospital. Inside of these white blood cells, Miescher isolated a substance that was high in phosphorus and nitrogen. It was present in every cell he examined. Miescher named this new substance nuclein. -
Chargaff's Contribution
The second contribution to the structure of DNA was made by a scientist named Erwin Chargaff. Chargaff is known for the creation of Chargaff's Rule in which he stated, in base pairs the number of guanine units equals the number of cytosine units, and the number of adenine units equals the number of thymine units. In his experemints, Chargaff isolated DNA from many organisms and found that the same organisms share equal amounts of the same base pairs. -
Chargaff's Discovery
Chargaff's discovery improved upon our current understanding of DNA by showing the composition of DNA in the form of base pairs. Chargaff's discovery would later influence the work of scientists Watson and Crick to develop the DNA structure as a double helix. -
Franklin's Contribution
The third contribution to the structure of DNA was made by a scientist named Rosalind Franklin. Franklin is known for discovering that DNA is in the shape of a helix. Franklin used a method called X-ray diffraction to take images of DNA molecules. These images proved that the shape of the DNA structure was a double helix. Franklin was also able to infer that the nitrogenous bases were located in the center of the helix while sugars and phosphates were located on the backbone of the structure. -
Franklin's Discovery
Franklin's discovery improved upon our current understanding of DNA by further defining the shape of the DNA structure. Before Franklin's images there was no conclusive information about DNA's exact shape. Franklin's observations were overlooked at the time of her discovery but were crucial as Watson and Crick used her model t construct the 3D Double Helix Model. -
Hershey and Chase's Contribution
The fourth contribution to the structure of DNA was made by two scientists named Martha Chase and Alfred Hershey. Chase and Hershey are known for their experiments on the genetic structure of viruses. In their experiments, viruses were grown in cultures containing radioactive isotopes of phosphorus and sulfur. Bacteria was then mixed with the healthy cells and the virus was allowed to inject itself into the cell. When the cell was examined again, DNA was spread to the cell and not proteins. -
Hershey and Chase's Discovery
Hershey and Chase's discovery improved upon our current understanding of DNA by proving that DNA was a part of every living cell. Their experiment also confirmed that DNA was responsible for the genes and traits passed down from parent cells and not proteins. -
Watson and Crick's Contribution
The fifth contribution to the structure of DNA was made by scientists James Watson and Francis Crick. Watson and Crick are known for developing the double helix or "twisted ladder" structure of DNA. Acknowledging the past efforts in DNA discoveries from Franklin and Chargaff, Watson and Crick were able to successfully construct a 3D model of the double helix. This 3D model showed base pairs as the rungs of the ladder while sugars and phosphates served as the rails. -
Watson and Crick's Discovery
Watson and Crick's discovery improved upon our current understanding of DNA by creating the first complete model of the DNA structure. Watson and Crick's model not only showed what the DNA molecule looked like but also its function. The Watson and Crick Model proved that the double helix form was used for DNA replication in a cell. -
Meselson & Stahl's Discovery
Meselson and Stahl's contribution improved upon our current understanding on DNA by confirming the way that DNA replicates itself. Meselson and Stahl showed that when DNA replicates itself, one strand of nucleotides will be new while one strand will be from the split DNA. -
Meselson & Stahl's Contribution
The final contribution to the structure of DNA was made by two scientists Matthew Meselson and Franklin Stahl. Meselson and Stahl are known for performing experiments that confirmed DNA replication was semi-conservative. For these experiments, Meselson and Stahl used an isotope to track the patterns of DNA in a bacteria across generations. They found that the DNA replicated semi-conservatively.
