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Friedrich Miescher
Miescher did most of his work in 1869, but his paper on nuclein was not published until 1871. Nuclein was a new molecule from the nucleus that he had experimented with and isolated. He determined it was made up of hydrogen, oxygen, nitrogen, and phosphorus. He also determined that there was a unique ratio of phosphorus to nitrogen. Miescher used the puss from used bandages for his studies. -
Frederick Griffith
Griffith was studying two strains of Streptococcus Pneumonia that varied drastically in appearance and their ability to cause disease. He experimented with the strains by injecting them into mice. By doing this, he observed and hypothesized that a chemical component from the virulent S cells had somehow transformed the R cells into the more virulent S form. -
Oswald Avery, Maclyn McCarty, and Colin McCleod
In 1944, Avery showed that nucleic acid, DNA, was the chemical basis for specific and apparently heritable transformations in bacteria. With the information from previous studies on Pneumonia, they experimented with the cells' transformations. The three tried to purify-from some twenty gallons of bacteria-what Abery called the "transformation factor". -
Erwin Chargaff
Erwin Chargaff investigated the composition of DNA. He demonstrated the three rules of DNA.
1) The number of adenine residues always equals the number of thymine residues
2) The number of guanine residues always equals the number of cytosine residues
3) The number purines (A+T) always equals the number of pyrimidines (T+C) (this rule is a consequence of rules 1 and 2) -
Linus Pauling
Pauling originated the concept of molecular disease. He discovered that sickle cell anemia might be caused by a defect in the red blood cell's hemoglobin. After years of research, he identified the disease as a molecular origin-caused by a genetically transmitted abnormality in the hemoglobin molecule. -
Alfred Hershey and Martha Chase
Hershey and Chase discovered that DNA is the genetic material. Through his studies, Hershey learned that phage could recombine when it was co-infected with the bacterial host. He is well known for his experiment that showed how DNA is a principal component entering the host cell during the infection. -
Rosalind Franklin and Maurice Wilkins
Franklin and Wilkins worked together to make crucial contributions to the discovery of DNA's structure. For his studies in the early years, Maurice Wilkins used optical spectroscopy. Their discovery in 1953 revealed the physical and chemical basis of how characteristics are passed down through the generations and how they are expressed in individual organisms. -
James Watson & Frances Crick
Watson and Crick announced that human DNA is in a double-helix structure. They determined that it is a double-helix polymer, each strand containing a long chain of monomer nucleotides wrapping around each other. In their findings, they stated that DNA replicated itself by splitting into two identical strands, then becoming the template for the new DNA. Their discoveries directly led to pre-scannings for genetic diseases, the ability for genetic engineering, and design to treat genetic diseases. -
Matthew Meselson & Franklin Stahl
Meselson and Stahl demonstrated that each daughter DNA strand contained one subunit from one parent, and the other subunit from the other. This also verified Watson and Crick's experiment. Meselson and Stahl's esperiment led to proving how DNA replicates, which can provide a basis for understanding hereditary and genetic diseases. -
Paul Berg
Berg discovered gene-splicing by wrapping a bit of DNA with another type of DNA from a virus strand. They way they looped around each other, it combined and slightly altered the DNA from the two species. This was the first man-made recombinant DNA strand to be made. After this discovery, Berg continued to work in this field of research, but did not make any sounding discoveries or experiments. -
Frederick Sanger
Sanger created the rapid-DNA-sequencing technique to find the order of bases in strands of DNA using E. coli virus strands. He discovered that you can add enzymes to synthesize pieces of DNA. He then used a radioactive marker to identify the individual bases. Sanger is one of four people to win two Nobel Prizes for his work. -
Barbara McClintock
McClintock studied corn's hereditary characteristics, specifically what made the kernels different colors. She studied how these traits passed down from parents to offspring, and she linked this to chromosomes. She stated that genetic elements can sometimes change position on a chromosome, making nearby genes active or inactive, which is what changed the color of the kernels on the corn. -
Kary Mullis
Mullis invented the process called the polymerase chain reaction. This reaction can copy a small amount of DNA into large quantities over a short period of time. Mullis's experiment used heat to sepapate DNA, and with DNA polymerase, two new strands of DNA formed. His experiment and research has played a very important role in medical and forensics research. -
J. Craig Venter
Venter worked on the human genome project, but after a controversy, he went on to research in his own lab. He came up with the shotgun sequencing method, which he believed was the best and fastest way to get useful genome data. The Human Genome Project rejected it since it wasn't accurate enough. However, Venter is still the first person to sequence and analyze a human genome.
