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Friedrich Miescher
Friedrich Miescher contributed to DNA research when he isolated molecules that made up cells. He was studying white blood cells and used pus from bandages to study. He found a substance in it known as nuclei. Miescher isolated nuclein from the nucleus and determined that nuclein is made up of hydrogen, oxygen, nitrogen and phosphorous. An interesting fact about Miescher is that in 1855 he founded Switzerland’s first physiological institute. -
Frederick Griffith
Griffith studied pneumonia-causing bacteria and studied the R and S strands. The R strand is known to be harmless and the S strand is lethal. Frederick used the Rand S strands in experiments with mice to see if they had the ability to cause pneumonia. Heat was able to destroy the S strands ability to cause pneumonia, but the hereditary material from a dead S cell goes to R. The descendants of the transformed R cell had the ability to kill mice. -
Erwin Chargaff
Chargaff was the one to discover that the amounts of adenine and thymine in DNA are roughly the same, as well as guanine and cytosine. This was known as Chargaff's first rule of base pairing. Erwin's second rule of base pairing states that relative amounts of adenine, thymine, cytosine and guanine bases differ depending on the species. This led to a further thought that instead of protein, DNA could be the gentic material . -
Oswald Avery, Maclyn McCarty and Colin McCleod
These researchers were able to show that DNA can transform the properties of cells. They studied streptococcus pneumonia bacteria and discovered that DNA is a "transforming principle". Oswald, Maclyn and Colin worked together to purify the bacteria and show that DNA is a transforming factor. Oswald Avery represented that DNA is the chemical basis for specific and heritable transformations in bacteria. I found it interesting that Avery was one of the first people to study immunochemistry. -
Barbara McClintock
McClintock discovered that some genes could be mobile or moving around, she created staining technique to see the maize chromosome, which helped her to discover chromosome breakage in DNA. The chromosome breakage happened in maize chromosome 9. It led her to name the chromosome “Ds” or “dissociations”. She studied that Ds could change position within themselves. The discovery took a decade to be recognized by other people. McClintock received two Nobel Prizes (physiology and medicine) in 1983. -
Linus Pauling
Linus Pauling studied x-ray diffraction. With his studies, he was able to determine the shape of proteins. This then provoked the study of DNA double helix, leading to the knowledge of how amino acids fit together to make proteins. Pauling also discovered the alpha helix of globular protein. This allowed the difference of hemoglobin between people with and without sickle cell. An interesting fact about Linus Pauling is that he is the only person to receive two unshared Nobel Peace prizes. -
Alfred Hershey and Martha Chase
Both Hershey and Chase contributed by assisting in the confirmation that DNA is a genetic material. They showed that when bacteriophages infect bacteria the DNA enters the host cell. When either DNA or protein is injected into the host cell the bacterium creates many phages. Hershey and Chase then whirled the different culture of bacteria into blenders. The blender seperated the bacteria from phage, causing a pellet or supernatant. Eventually, they were able to measure radioactivity as well. -
James Watson and Frances Crick
Watson and Crick discovered that DNA is double helix and looks like a twisted ladder. To test their hypothesis, they connected balls (DNA bases) with stick (bonds). The bases are cytosine, thymine, adenine, and guanine. After connecting balls together ( A to T, C to G), they created a model look like a twisted ladder. They concluded and published their work to the world. Their discovery of DNA marked one of the most important event in science. The two shared a noble prize in Physiology in 1962. -
Rosalind Franklin and Maurice Wilkins
Franklin and Wilkins worked with x-ray crystallography. From this, they were able to produce two high-resolution photos of crystallized DNA. The photos led to the determination of the basic dimensions of DNA strands. Analyzing the photos also led to the discovery that phosphates were on the outside of, most likely, a helical structure. Wilkins used x-rays to create diffraction images of DNA molecules. Combined, Wilkins' and Franklin's photos led to the helical nature of DNA. -
Matthew Meselson and Franklin Stahl
Meselson and Stahl found out that each daughter DNA molecule has one new daughter subunit and one from the parental DNA molecule. First, they used density-gradient centrifugation to separate different molecule in DNA, which also separated parent DNA and daughter DNA. Then, they put 15N into parental DNA and found out it replicated. They announced their discovery in 1958. The two supported the experiments from Jame Watson and Frances Crick. They did their experiment at Caltech in Pasadena, Cali. -
Paul Berg
Berg is known for recombinant DNA. First step of his experiment was to cut a small part of virus (SV40) DNA strand out with an enzyme (EcoRI), and connected it with DNA of another virus (Lambola). To connect two DNA together, he had to use two enzymes that was made by Stanford colleagues. Finally, two DNA combined together, and Berg announced the first man-made recombinant DNA. Berg got his Noble prize in chemistry in 1980 along with Frederick Sanger. He also graduated from Penn State college. -
Frederick Sanger
Sanger founded the sequence of DNA. He created his own method calls “rapid DNA sequencing” which to determine the order of the bases in a strand of DNA. Sanger tested the method on a bacterial virus calls phiX174. He and his team was able to identified 5000 letters long in the bacteria’s DNA. Then, he moved on to human and identified 16000 letters long. People still use his method today. Before find out DNA sequence, he worked on finding the structure of protein in 1955. He won two Nobel prize. -
Kary Mullis
Mullis is famous for his discovery of polymerase chain reaction (PCR), a process that allow a specific strand of DNA to be copied multiple times in a short period of times. He failed at first because his choice of polymerase kept being destroyed at 95 centigrade (high temperatures). He found new one calls “Thermus aquaticus” or “Taq”, and this one could sustain the high temperature. Mullis tested PCR at Cetus Corporation. He received a Nobel prize in chemistry in 1993, and Japan Prize as well. -
J. Craig Venter
Venter is known for leading the first draft sequence of human genome. He created a method calls “Shotgun sequencing”. This method collected the human genome data faster and more effective than some other methods according to Venter. He also created a team to transfer a cell with a synthetic chromosome. His work was inspired when he was still in Vietnam and fought the Vietnam War. J Craig Venter is the founder of Celera Genomic and J. Craig Venter Institute.
