Was the first person to work on DNA. He isolated a new substance from the nuclei of white blood cells. After the discovery that cells were the basic unit of life, Meischer was interested in their chemical components.Adding alkali to white blood cells he made them burst open and from it he extracted DNA, which at the time he called 'nuclein'
He was the first to discover the order of the three major components of a single nucleotide; the first to discover the carbohydrate component of RNA; the first to discover the carbohydrate component of DNA; and the first to correctly identify the way RNA and DNA molecules are put together.
Levene proposed that nucleic acids were composed of a series of nucleotides, and that each nucleotide was constructed of one of four nitrogen-containing bases, a sugar molecule, and a phosphate group.
Two major facts were already known about DNA. The first was that it is contained in the nucleus of every living cell. The second was that, in addition to sugar and phosphate, DNA was composed of two bases: pyrimidines, of which there are two types (cytosine and thymine), and purines, of which there are also two types(adenine and guanine).
He discovered that adenine and thymine existed in equal proportions in all organisms, aswell as cytosine and guanine, and that the proportions between the two pairs were different depending on the organism.
From his research Chargaff drew the conclusion that it was the DNA in the nucleus of the cell that that carried genetic information rather than the protein.
Like Franklin, his partner at a time before they went their seperate ways, Wilkins was using X-Ray diffraction to study DNA and sperm heads. He like Franklin discovered the well defined helix patterns that led to the deriving of the molecular structure of DNA by Watson and Crick.
Made a crucial contribution to the discovery of the double helix structure of DNA using X-ray crystallography.
Whithout her 'photo 51' Watson and Crick may have never completed their work.
Up until this time no progress in the study of DNA had been made since Chargaff's idea of a double helic structure.
Watson and Crick were not the discoverers of DNA, but they were the first scientists to construct a detailed three dimensional model of the molecules complex double-helical Structure.
Francis Crick had speculated that protein creation must involve some sort of template molecule. It was found by American Biochemists Hoagland and Berg (independent) who isolated strands of RNA in the cytoplasm, they discovered that each was configured to capture a different amino acid. Further finding that different sequences of these short RNA strands (tRNA) would determine the assembly pattern for different proteins.
After Hoagland and Berg's discovery of RNA assembly patterns, Monod and Jacob identified the molecular courier system that reads instructions from a DNA sequence in the nucleus and carries it out to protein factories in the cell body. Effectvely establishing a fundamental principle of molecular genetics.