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While studying white blood cells in pus from surgical bandages, Miescher isolated a new substance in cell nuclei. He observed that it had acidic properties and named it nuclein, although its function was unknown. This was the first discovery of DNA as a molecule. -
He identified the building blocks of DNA as the four nitrogenous bases: adenine (A), thymine (T), cytosine (C), and guanine (G).
The sugar deoxyribose.
The phosphate group.
He defined the nucleotide as being made up of sugar + phosphate + base.
He proposed the tetranucleotide model, according to which DNA was formed by a simple repetition of the four bases.
Because of this theory, it was thought for decades that DNA was too simple to carry genetic information.