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Friedrich Miescher
Miescher determined that DNA is not a protein, and that it is rich in nitrogen and phosphorus, but he never learned its function. He isolated "nuclein," DNA with associated proteins, from cell nuclei. He was the first to identify DNA as a distinct molecule. -
Frederick Griffith
British bacteriologist Frederick Griffith was studying pneumonia-causing bacteria hoping to create a vaccine. He isolated two types of bacteria, on harmless (R), and the other lethal (S). He discovered that heat destroyed the ability of lethal (S) bacteria to cause pneumonia, but it did not destroy their hereditary material. -
Oswald Avery, Maclyn McCarthy and Colin McCleod
The group found that a pure extract of the "transforming principle" was unaffected by treatment with protein-digesting enzymes, but was destroyed by a DNA- digesting enzyme. Their experiment showed that the transforming principle is DNA, and, by extension, a gene is made of DNA. -
Linus Pauling
Pauling established that sickle-cell anemia was a molecular disease caused by an abnormal hemoglobin molecule and the abnormal hemoglobin was caused by just a single amino acid anomaly in one of the polypeptide chains. -
Erwin Chargaff
Erwin Chargaff showed that the composition of DNA from various samples revealed that the content of purines equaled the content of pyrimidines. A=T; C=G. -
Barbara McClintock
Barbara discovered mobile genetic elements. Many characteristics of organisms are determined by heredity which are stored in the chromosomes inside their cells' nuclei. She studied corn's hereditary characteristics. Barbara proved that genetic elements can sometimes change position on a chromosome and that this causes nearby genes to become active/inactive. -
Alfred Hershey and Martha Chase
Alfred Hershey and Martha Chase proved that DNA, and not protein, satisfies the first property of a hereditary molecule: It transmits a full complement of hereditary information. Hershey and Chase carried out am elegant series of experiments proving that the material bacteriophage injects bacteria into DNA, not protein. -
Rosalind Franklin and Maurice Wilkins
Wrote a paper that alternating deoxyribose and phosphate molecules form the twisted uprights of the DNA ladder. The rungs of the ladder are formed by complementary pairs of nitrogen bases. A with T and G with C. -
Jame Watson and Frances Crick
Cambridge university scientists James and Frances told the world they determined the double-helix structure of DNA (the molecule containing human genes). They solved how it was possible for genetic instructions to be held inside organisms and passed from generation to generation. -
Matthew Meselson and Franklin Stahl
Matthew and Franklin invented the technique of density gradient and proved DNA replication was semiconservative. They called it density gradient centrifugation. It uses centrifugal force to separate molecules based on their density. -
Paul Berg
Paul spent a year experimenting with polyoma and SV40 tumor viruses in mammalian cell cultures. He used SV40 to introduce new genes to mammalian cells. He developed a way to join two DNAs together. This led to the recombinant DNA tech, providing a major tool for analyzing mammalian gene structure. -
Frederick Sanger
Frederick developed methods to determine the sequence of building blocks making up protein insulin. Over 15 years Fredrick and a team came up with ways to sequence DNA.The Sanger DNA sequencing method shows 500-800 bases could be read at a time. -
Kary Mullis
Kary invented the process known as polymerase chain reaction, large amounts of DNA can be copied in a short amount of time. Applying heat, DNA's two strands are separated and DNA building blocks that were added are bonded to each. With the help of an enzyme, new DNA chains are formed and it can be repeated. -
J. Craig Venter
Craig came up with a quicker and faster method. He called it whole genome shotgun sequencing. Using machines machines and a civilian super computer, he finished the human genome in just three years
