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Friedrich Miescher
While Miescher was working under Ernst Hoppe-Seyler at the University of Tubingen, he discovered a substance containing both phosphorus and nitrogen in the nuclei of white blood cells found in puss. The substance became known as nuclein, because it had seemed to come from cell nuclei. This was arguably his biggest contribution made to science. After Miescher separated the substance into protein and acid components, it earned its new name, nucleic acid. -
Oswald Avery, Maclyn McCarty & Colin McCleod
Avery and his colleagues MacLeod and McCarty announced that DNA is a hereditary agent in a virus from a harmless to a pathogen version. Their achievement was based on Frederick Griffith’s studies on bacteria, believing that bacteria types were not changeable from one to another generation. During their experiment, the trio refined the purification process until the result was a cell extract whose amounts of carbon, hydrogen, nitrogen, and phosphorus corresponded to those of DNA. -
Alfred Hershey & Martha Chase
Alfred Hershey and Martha Chase worked on a series of experiments that helped to confirm that DNA is genetic material. DNA had been previously known to biologists, but they had assumed that proteins carried the information for inheritance because DNA appeared to be an inert molecule. Hershey and Chase showed that when bacteriophages, which are composed of DNA and protein, infect bacteria, their DNA enters the host bacterial cell, but most of their protein does not. -
James Watson & Frances Crick
Watson and Crick announced that they had determined the double-helix structure of DNA, the molecule containing human genes. In the beginning of 1953, Linus Pauling suggested an incorrect model of DNA, which prompted Waston and Crick to try again and beat Paul. They determined that the structure of DNA was a double helix polymer each containing a long chain of monomer nucleotides. According to their findings, DNA replicated itself by separating into individual strands. -
Linus Pauling
Pauling discovered the alpha-helix and the beta-sheet in a DNA molecule. Because Pauling determined the alpha helix of globular proteins, he was able to contribute to the discovery of the difference in the hemoglobin between people without sickle-cell. -
Rosalind Franklin & Maurice Wilkins
Wilkins began using optical spectroscopy to study DNA in the late 1940s. Then, in the 1950s, he and co-worker Ray Gosling obtained the first clearly crystalline X-ray diffraction patterns from DNA fibres. In 1953, Wilkins discovered the structure of DNA, which helped to reveal the physical and chemical basis of characteristics passed down through generations. Rosalind Franklin also collaborated with Gosling in 52’ and took the infamous ‘Photo 51’. -
Matthew Meselson & Franklin Stahl
Meselson and Stahl discovered the semi-conservative replication of DNA; when each strand of DNA makes a template to create a new complementary strand. Meselson and Stahl used an isotope to track the patterns of DNA in bacteria across generations. -
Erwin Chargaff
Erwin Chargaff’s most famous observation was that DNA varies from species to species. He made two important discoveries/rules. First, that the amounts of thymine and adenine are identical in any DNA molecule, as are the amounts of cytosine and guanine. Second, that the DNA of different species differs in its proportions of adenine and guanine. -
Paul Berg
Berg performed a number of gene-splicing experiments. As a result, the first human-made recombinant of DNA was made. -
Barbara McClintock
McClintock discovered that some genes could be mobile. She produced the first genetic map for maize, linking regions of the chromosome to physical traits. -
Frederick Sanger
Sanger discovered what is known as the “Plus and Minus Method”, used for rapid DNA sequencing. In his experiments, DNA was used and synthesized from templates to make sets of DNA. -
Frederick Griffith
Griffith discovered that hereditary information passes between two strains of bacteria. He worked as a British bacteriologist and mainly focused on epidemiology and pathology of bacterial pneumonia. He reported the first widely accepted demonstrations of bacterial transformation, this is now known as Griffith’s Experiment. -
Kary Mullis
Kary Mullis discovered the DNA polymerase chain reaction. While driving, he had the idea to use a pair of primers to bracket the desired DNA sequence and to copy it using DNA polymerase; a technique that would allow rapid amplification of a small stretch of DNA and become a standard procedure in molecular biology laboratories. This technique allows a specific stretch of DNA to be copied billions of times in only a couple hours. -
J. Craig Venter
Venter pioneered techniques in genetics and genomics research. He is known for leading the first draft sequence of the human genome and assembled the first team to transfect a cell with a synthetic chromosome. Venter and Francis Collins of the National Institutes of Health and U.S. Public Genome Project jointly made the announcement of the mapping of the human genome.
