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Discovering DNA
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Gregor Mandel
Mendel's pea plant experiments conducted between 1856 and 1863 established many of the rules of heredity, now referred to as the laws of Mendelin inheritence. -
Friedrich Meischer
He was the first researcher to isolate and identify nucleic acid. -
Walther Flemming
He found that a certain class of dyes revealed a threadlike material in the nucleus. Applying these stains to cells killed at different stages of division, he prepared a series of slides that, upon microscopic examination, clearly established the sequence of changes occurring in the nucleus during cell division. He showed that the chromosomes shortened and seemed to split longitudinally into two halves, each half moving to opposite sides of the cell. He named the entire process mitosis. -
Thomas Hunt Morgan
He discovered chromosomes play a role in heredity. -
Frederick Griffith
He was a British bacteriologist whose focus was the epidemiology and pathology of bacterialpneumonia. He reported what is now known as Griffith's Experiment, the first widely accepted demonstrations of bacterial transformation, whereby a bacterium distinctly changes its form and function. -
George Beadle and Edward Tatum
Showed that genes direct the synthesis of enzymes that control the metabolic process. -
Erwin Chargaff
He discovered two rules about DNA. The first rule was that in DNA the number of guanine units equals the number of cytosine units, and the number of adenine units equals the number of thymine units. This hinted at the base pair makeup of DNA. The second rule was that the relative amounts of guanine, cytosine, adenine and thymine bases varies from one species to another. This hinted that DNA rather than protein could be the genetic material. This lead to discovering the shape of the DNA strands. -
Oswald Avery, Maclyn McCarty, and Colin MacLeod
They discovered that DNA is the substance that causes bacterial transformation, in an era when it had been widely believed that it was proteins that served the function of carrying genetic information. -
Fred Sanger
His first triumph was to determine the complete amino acid sequence of the two polypeptide chains of bovine insulin, A and B. -
Alfred Hershey and Martha Chase
They suggested that only DNA is needed for viral replication. Using radioactive isotopes 35S to track protein and 32P to track DNA, they show that progeny T2 bacteriophage isolated from lysed bacterial cells have the labeled nucleic acid. Further, most of the labeled protein doesn’t enter the cells but remains attached to the bacterial cell membrane. -
Rosalind Franklin
She discovered the shape of DNA aka the “double helix”. -
James Watson, Francis Crick, and Maurice Wilkins
They were credited with discovering the structure of DNA. -
Jon Hin Tijo
He was an Indonesian-American cytogeneticist renowned as the first person to recognize the normal number of human chromosomes. This epochal event occurred at the Institute of Genetics of the University of Lund in Sweden, where Tjio was a visiting scientist. -
Matthew Meselson and Franklin Stahl
The Meselson–Stahl experiment was an experiment by Matthew Meselson and Franklin Stahl in 1958 which supported the hypothesis that DNA replication wassemiconservative. In semiconservative replication, when the double stranded DNA helix is replicated each of the two new double-stranded DNA helixes consisted of one strand from the original helix and one newly synthesized. -
Marshall Nirenberg
Marshall and a group of scientists broke the genetic code.
