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Friedrich Miescher
Friedrich worked with leukocytes as his source material, which are white blood cells of the immune system. He looked into the proteins in these cells. While experimenting, he had obtained the first crude purification of DNA. Friedrich was also the first person to identify DNA as a distinct molecule. I personally found it interesting that he found a substance with phosphorus and nitrogen in the nuclei of white blood cells found in pus. -
Linus Pauling
Linus Pauling both founded the spiral structure of proteins, contributing to the discovery of DNA, and deduced rules of interpreting X-ray diffraction helping him discover the shape of proteins and provoked the discovery of the DNA double helix. This was so important since DNA was discovered by an X-ray -
Frederick Griffith
In 1928, Frederick used Streptococcus pneumoniae, a bacterium that causes pneumonia, to demonstrate bacterial transformation. He used two strains of the bacterium, rough and smooth. From the experiment, he learned that injecting the S strain into the mouse killed them from pneumonia while injecting the mouse with the R strain did not. This helped discover the process called transformation in DNA which is a step in DNA cloning. -
Barbara McClintock
Barbara had discovered that some genes could be mobile. She proved that genetics can change positions on chromosomes which could cause the gene to be either active or inactive. Jumping genes are also DNA sequences so this showed how genes could move. I find it very interesting that the mobile genes could alter expressions of other genes which is pretty cool. -
Frederick Sanger
Frederick studied the free amino groups in insulin and figured out ways to order the amino acids. This helped him that proteins were ordered molecules and the genes and DNA that make the proteins should have an ordered sequence also. I find it interesting that he was able to discover that there is a genetic code to DNA which helped for the study of DNA. -
Oswald Avery, Maclyn McCarty & Colin McCleod
The three men discovered that DNA can transform the properties of cells, clarifying the chemical nature of genes. They studied the Streptococcus pneumoniae and Frederick Griffith's experiment to then be able to identify DNA as the “transforming principle”. I found it interesting how scientists use each other’s work for their experiments very often. -
Erwin Chargaff
Erwin discovered that DNA varies from species to species which helped the realization that DNA was genetic material. He also discovered that whether it was taken from a plant or animal, it contained equal amounts of adenine, thymine, cytosine, and guanine. These gave clues into chemical pairings that make up the double helix. I find it interesting that he was able to make two major discoveries. -
Rosalind Franklin & Maurice Wilkins
Rosalind and Maurice discovered together the first clear crystalline X-ray diffraction from DNA fibers. Rosalind's Photo 51 was created with the help of Wilkins' work 4 years prior. I find it interesting how the structure of DNA was discovered from an X-ray. -
Alfred Hershey & Martha Chase
Alfred and Martha had conducted experiments and discovered that genes were made of DNA. The experiment was called the Waring Blender experiment. In the experiment, they analyzed what happens when phases infect the bacteria and determined that the replicated pieces of phages entering bacteria during infection, the genetic parts are DNA. I found it interesting that when reading the article on them, I realized they conducted many experiments that all were very effective. -
James Watson & Frances Crick
James and Frances studied X-ray crystallography and worked on molecule models in order to find DNA. With the X-rays from Franklin, they successfully found the structure of DNA. I find it interesting how they discovered the structure from making models out of cardboard and ended up being successful. -
Matthew Meselson & Franklin Stahl
Matthew and Franklin tested the hypothesis of DNA replication in order to find what DNA replication model was the correct explanation. The experiment was that they grew E. coli cells with nitrogen present so they could label all the DNA molecules. This also allowed them to track the parental DNA. I find the method to label the DNA was interesting. -
Paul Berg
Paul Berg successfully inserted DNA from bacteria into the virus's DNA. Meaning, he had created the first DNA molecule made from parts from different organisms. His experiment was to cut the loops, where the DNA occurs in viruses, in one place of an enzyme. Then he made the ends sticks together again by modifying them with two other enzymes. The two types of DNA were mixed together and rejoined into loops and new loops combined DNA. This was the first man made DNA molecule. -
Kary Mullis
Kary had developed PCR, which is a method used to make copies of specific DNA samples. This allows scientists to be able to take small samples of DNA and study it. Being able to do that is very helpful since the smallest amount of DNA can still be studied with PCR. I find it interesting how PCR is made since it is not how I would expect it to be made. -
J. Craig Venter
Craig created the EST method of finding genes. He displayed it as a cheaper and faster method than the human genome project. In EST, DNA is sequenced using an automated DNA sequencing machine. The ESTs are long enough afterwards to be to be told from one another. I find the process of sequencing DNA interesting and I would like to look more into it on my own time.
