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Friedrich Miescher
Miescher first described the substance DNA after he extracted it from cell nuclei. Miescher determined that DNA is not a protein, and that it is rich in nitrogen and phosphorus, but he never learned its function. I found it interesting that he was one of the first to discover that carbon dioxide levels in blood regulated breathing. -
Frederick Griffith
Griffith studied pneumonia-causing bacteria in the hopes of making a vaccine. By isolating 2 strains of bacteria and using them in a set of experiments on mice, Griffith discovered that heat destroyed the ability of lethal S bacteria to cause pneumonia, but it did not destroy their hereditary material. I found it interesting that Griffith developed a reputation for his thorough and methodical research. -
Oswald Avery, Maclyn McCarty & Colin McCleod
Avery, MacLeod, & McCarty decided to identify the “transforming principle” Griffith had found. They extracted lipid, protein, and nucleic acids from S cells, then used a process of elimination to determine which transformed bacteria. They realized the substance they were seeking must be nucleic acid. DNA-degrading enzymes destroyed the extract’s ability to transform cells, but RNA-degrading enzymes didn't. It was interesting that they had assumed that proteins were the material of heredity. -
Erwin Chargaff
Erwin Chargaff discovered the amounts of thymine and adenine are identical in any DNA molecule, as are the amounts of cytosine and guanine and that the DNA of different species differs in its proportions of adenine and guanine. I found it interesting that this was a major break from what scientists had believed until then. -
Alfred Hershey & Martha Chase
Alfred Hershey and Martha Chase proved that DNA, and not protein, satisfies the first expected property of a hereditary molecule: It transmits a full complement of hereditary information. Hershey and Chase worked with bacteriophage, a type of virus that infects bacteria. Hershey and Chase carried out experiments proving that the material a bacteriophage injects into bacteria is DNA, not protein. I found it interesting that they conducted their experiments at the Carnegie Institute of Washington. -
Rosalind Franklin & Maurice Wilkins
Biochemist Rosalind Franklin had also been working on the structure of DNA. Franklin specialized in x-ray crystallography, a technique in which x-rays are directed through a purified and crystallized substance. Franklin made the first clear x-ray diffraction image of DNA as it occurs in cells. I found it interesting that she used the image to calculate that a DNA molecule is very long compared to its diameter of 2 nanometers. -
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. Sanger won his first Nobel Prize for Chemistry in 1958 for his work on the structure of protein. I found it interesting that he won 2 Nobel Peace Prizes -
Linus Pauling
In the 1950's, Linus Pauling became known as the founder of molecular biology due to his discovery of the spiral structure of proteins. Pauling's discoveries contributed to Watson and Crick's breakthrough of the DNA double helix. I found it interesting that Pauling received a Nobel Peace Prize. -
Watson & Crick
Watson and Crick built the first accurate model of DNA. They pestered chemists to help them identify bonds they might have overlooked, fiddled with cardboard cutouts, and made models from scraps of metal connected by suitably angled “bonds” of wire. I found it interesting that Watson and Crick conveniently forgot to credit Franklin for her data. -
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. The Meselson-Stahl experiment enabled researchers to explain how DNA replicates, thereby providing a physical basis for the genetic phenomena of heredity and diseases. I found it interesting that Meselson & Stahl's experiments helped cement the concept of the double helix. -
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 found it interesting that he is the father of genetic engineering. -
Barbara McClintock
Barbara McClintock made discovery after discovery over the course of her long career in cytogenetics. But she is best remembered for discovering genetic transposition (“jumping genes”). I found it interesting that she was the first American woman to win an unshared Nobel Prize. -
Kary Mullis
Kary Mullis invented the process known as polymerase chain reaction (PCR), 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 found it interesting that PCR can be used to amplify a sample of DNA when there isn't enough to analyze -
J. Craig Venter
Venter pioneered new techniques in genetics and genomics research and headed the private-sector enterprise, Celera Genomics, in the Human Genome Project (HGP). He developed an alternative technique using expressed sequence tags (ESTs), small segments of deoxyribonucleic acid (DNA) found in expressed genes that are used as “tags” to identify unknown genes in other organisms, cells, or tissues. I found it interesting that he established the Institute for Genomic Research.
