The Discovery of DNA - Ade, Lauren

Friedrich Miescher

1869

Friedrich Miescher was a scientist who studied white blood cells in particular. He managed to isolate a new molecule "nuclein" from the pus on used band-aids and salmon sperm, making it evident that DNA is its own molecule. This newfound molecule set the groundwork for later molecular discoveries.

Frederick Griffith

1928

Frederick Griffith tested Streptococcus pneumonia bacteria on mice when he found that there are rough bacteria, which fight pneumonia, and smooth bacteria, which kill the organism. He inserted heat-killed smooth bacteria in the mice, and they lived; he inserted heat-killed smooth bacteria and rough bacteria, and the mice died. Overall, Griffith found that rough strain bacteria took up a transforming principal, meaning bacteria can transform.

Oswald Avery, Maclyn McCarty, and Colin McCleod

1944

Avery continued Griffith's work by trying to figure out what caused the bacteria to transform. Avery, McCarty, and McCleod found that DNA carries a cells genetic material and can be transformed. They tested with bacteria and mice to discover their findings.

Linus Pauling

1948

Linus Pauling dedicated his life to biologic molecular structures and the discovery of the alpha helix and beta sheet in protein structures. He was able to find the protein structures by X-Ray diffraction and a model he folded on paper. Without his work, Watson and Crick would have never been able to find the structure of DNA.

Barbara McClintock

1948

Barbara McClintock attended Cornell University. She tested corn chromosomes and came up with the "one gene, one enzyme" theory. Barbara found that chromosomal crossovers occur in corn chromosomes, so she further investigated, X-Rayed the corn and found that translocations, inversions, deletions, and ring chromosomes occurred. Overall, McClintock found that genetic elements are mobile.

Erwin Chargaff

1950

Erwin Chargaff published crucial facts that led to the discovery of DNA's structure. Erwin came up with the Chargaff rules: the number of adenine equals the number of thymine, the number of guanine equals the number of cytosines, and the number of adenine plus guanine equals the number of thymine plus cytosine. Erwin later shared this information with Watson and Crick, enabling them to become closer to finding the structure of DNA.

Rosalind Franklin and Maurice Wilkins

1951

Rosalind Franklin was intrigued by crystallography and managed to take the famous Photo 51; Photo 51 shows the helical shape of the DNA. Maurice Wilkins and Rosalind worked with this information together to try and figure out the structure of DNA. Unfortunately, Watson and Crick beat them to it, but Photo 51 taken by Franklin is arguably the most important piece of information to discover the structure of DNA.

Alfred Hershey and Martha Chase

1952

Hershey and Chase conducted a series of experiments to prove the DNA was the genetic material. They used viruses, T2 bacteriophage, grown in both radioactive sulfur and phosphorus and then tested them in the bacteria E. coli; the DNA was transferred to the bacteria meaning that DNA, is, in fact, genetic material.

James Watson and Frances Crick

1953

James and Frances worked at the Cavendish lab at Cambridge University. Together, Watson and Crick discovered the structure of DNA, a double helix. The scientists used Photo 51 and information that Rosalind Franklin and Maurice Wilkins produced to come to their grand discovery. The scientists won a Noble Prize for their scientific accomplishments.

Matthew Meselson and Franklin Stahl

1958

Matthew Meselson and Franklin Stahl found proof for Watson and Crick's model of the semi-conservative replication. They did this by using a new technique they created called the density gradient centrifugation which separates molecules based on densities. Overall, the scientists worked towards discovering all of the in-and-outs of DNA replication.

Paul Berg

1971

Paul Berg was the first to demonstrate making recombinant DNA. He tested Polyama, a murine virus, and SV40, a monkey virus in mammalian cell culture; he split two DNA molecules, one from a tumor cell, and one from E. coli bacteria and they produced the first recombinant DNA. Paul Berg received a Nobel prize in 1980.

Frederick Sanger

1977

Frederick Sanger attended Cambridge University and spent time researching amino groups in insulin. He was the first person to obtain a protein sequence and found that genes and DNA are what make up proteins. He also found that the genes and DNA that make up proteins are in a specific sequence. Sanger's worked along side other scientists to find the sequence of DNA.

Kary Mullis

1983

Kary Mullis invented the process known as polymerase chain reactions (PCR). PCR means that a small amount of DNA can be copied in large quantities over a short period of time. PCR has a made a huge impact on science, allowing causative agents of bacterial or viral infections to be identified from a little bit of DNA. Kary Mullis won a Nobel prize in 1993.

J. Craig Venter

2003

An interesting fact about Venter is that a lot of people view him as selfish and egotistical. Despite this, J. Craig Venter developed a method were small segments of DNA found in genes are used as tags to identify unknown genes in other organisms. He also created the Human Genome Project, and in 2000 completed a rough draft of the human genome sequence.