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Friedrich Miescher
The swiss physician who discovered DNA was Johann Friedrich Miescher. Friedrich Miescher first discovered DNA in 1870 by collecting white blood cells from pus and studied the nuclei of white blood cells. He also discovered and named this chemical substance that was rich in nitrogen and phosphorus atoms, Nuclein. This name progressed over time is now know as deoxyribonucleic acid. He identified DNA as part of a chromosome in 1871. -
Period: to
Dates 1870-1955
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Thomas Hunt Morgan
American zoologist and geneticist, famous for his experimental research with the fruit fly (Drosophila) by which he established the chromosome theory of heredity. He also discovered that there were sex chromosomes and that there were linked genes. For his discoveries concerning the role played by the chromosome in heredity, he was awarded the Nobel Prize in 1933. -
Frederick Griffith
Griffith discovered heat-killed pathogens, disease causing bacteria has a factor that can transform harmless bacteria into bacteria that can cause disease. He tested his theory on mice. He also looked at pneumonia bacteria trying to figure out a cure so that people would stop dying. Frederick also discovered that a substance passed from dead bacteria to live bacteria to change their phenotype. -
Oswald Avery
Avery and his colleagues repeated Griffith's experiment but made a extraction from the heat-killed bacteria. They treated the extract with enzymes that breakdown proteins, lipids, carbohydrates, other molecules, and RNA but transformation still occurred. They tried the experiment a second time, but used an enzyme that destroyed DNA. That time transformation did not occur. Avery and his colleagues discovered that DNA was the transforming factor. -
Erwin Chargaff
Erwin Chargaff discovered that the bases pairs Adenine and Thymine pair as well as Guanine with Cytosine. Through careful experimenting, Chargaff discovered two rules that helped lead to the discovery of the double helix structure of DNA. Chargaff's rule is that the amount of cytosine is approximately the same amount as guanine. -
Linus Pauling
Pauling discovered that a helix is the structure of a class of proteins. They also discovered the Beta Strand which is different polypeptide chains that run along side each other and linked together by hydrogen bonds which consist of 5-10 amino acids. Linus received The Nobel Peace Prize in Chemistry 1954 for his research into the nature of the chemical bond and its application to the elucidation of the structure of complex substances. -
Rosalind Franklin and Maurice Wilkins
Rosalind Franklin was an English chemist and X-ray crystallographer who was studying the structure of DNA using x-ray diffusion. Franklin diffracted the helical shape of DNA using uniformly oriented strands created by Maurice Wilkins. She also provided measurements of DNA while Wilkins provided the samples. -
Alfred Hershey and Martha Chase
The Hershey–Chase experiments were a series of experiments conducted in 1952 by Alfred Hershey and Martha Chase that helped to confirm that DNA is genetic material. In their experiments, 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. Their discoveries all served to prove that DNA is the hereditary material. -
James Watson and Francis Crick
Watson and Crick were building 3-D models of DNA out of cardboard and wire but were incorrect until they saw Franklin's x-ray patterns. After seeing her information, Watson and Crick made the first correct 3-D model of DNA and received The Nobel Prize in Physiology or Medicine 1962 for their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material.
