-
Friedrich Miescher
His contribution was extracting DNA from cell nuclei. Miescher determined that DNA is not a protein, and that it is rich in nitrogen and phosphorus. I think it is very interesting how long ago DNA was first extracted compared to when the function was discovered. -
Frederick Griffith
He isolated two strains (types) of the bacteria, one harmless (R), the other lethal (S). Griffith used R and S cells in a series of experiments testing their ability to cause pneumonia in mice. He discovered that the hereditary material passed from S cells to R cells proving that DNA holds hereditary information. I found it interesting that this scientist was able to learn about DNA using mice. -
Barbara McClintock
Barbara McClintock challenged existing concepts of what genes were capable of when she discovered that some genes could be mobile. Her studies of chromosome breakage in maize led her to discover a chromosome-breaking locus that could change its position within a chromosome. Interestingly enough, her discoveries have had an effect on everything from genetic engineering to cancer research. -
Oswald Avery, Maclyn McCarty & Colin McCleod
The scientists extracted lipid, protein, and nucleic acids from S cells used in Griffith’s experiment, then used a process of elimination to determine which transformed bacteria. They found that DNA was their answer, which proves Griffith’s claim that DNA carries hereditary information. I think it is interesting how the researchers were able to use enzymes to destroy lipids and proteins in the cell. -
Linus Pauling
Pauling used his knowledge of X-ray crystallography and his understanding of chemistry rules to determine how amino acids fit together to make proteins. He discovered the alpha-helix structure of proteins. I find it interesting that Pauling was able to discover that DNA is indeed a helix. -
Erwin Chargaff
Erwin first discovered that the amounts of thymine and adenine are identical in any DNA molecule, as are the amounts of cytosine and guanine. Also that the DNA of different species differs in its proportions of adenine and guanine. I find this last fact very interesting how different species DNA varies in adenine and guanine because it gives me more of an idea of what DNA is. -
Alfred Hershey & Martha Chase
Alfred Hershey and Martha Chase carried out experiments to determine the composition of the hereditary material that bacteriophage inject into bacteria. The experiments were based on the knowledge that proteins contain more sulfur (S) than phosphorus (P), and DNA contains more phosphorus than sulfur. I think the bacteriophage they used functioned interestingly. -
Rosalind Franklin & Maurice Wilkins
Franklin, who specialized in x-ray crystallography, made the first clear x-ray diffraction image of DNA as it occurs in cells. What blows my mind is the fact that Rosalind then went on to calculate the DNA’s lengths, and found it to be about 3.4 nanometers. -
James Watson & Frances Crick
Franklin’s image and data came to the attention of Watson and Crick, who now had all the information they needed to build the first accurate model of DNA. They discovered that DNA was a double helix structure. I find it interesting how fast Watson and Crick were able to make a model after retrieving Rosalind’s work. -
Frederick Sanger
He was the first person to obtain a protein sequence. By doing so, Sanger proved that proteins were ordered molecules and by analogy, the genes and DNA that make these proteins should have an order or sequence as well. I find it fascinating that Sanger spent a whole 12 years at work on his research. -
Matthew Meselson & Franklin Stahl
Matthew Meselson and Franklin Stahl invented the technique of density gradient centrifugation and used this to prove that DNA is replicated semi-conservatively. I think it's very interesting that DNA can split into two and act as a blueprint for new DNA to form. -
Paul Berg
Paul Berg succeeded in inserting DNA from a bacterium into the virus' DNA. He thereby created the first DNA molecule made of parts from different organisms. This type of molecule became known as "hybrid DNA" or "recombinant DNA". I think it's interesting that Berg was able to mix DNA from two different species. -
J. Craig Venter
He is known for discovering the coding of all the genes in a molecule of human DNA. I find it interesting that venter was able to find the coding of the DNA in humans because there has got to be a lot of it. -
Kary Mullis
Kary Mullis invented the process known as polymerase chain reaction, in which a small amount of DNA can be copied in large quantities over a short period of time. By applying heat, the DNA molecule's two strands are separated and the DNA building blocks that have been added are bonded to each strand. I find it interesting that by applying heat, DNA strands can be separated.
