Learn & Understand

The Molecule Nobody Understood: Miescher's Discovery of DNA

Long before anyone knew DNA carried the code of life, a young Swiss scientist isolated it from the pus of surgical bandages and gave it a name. For nearly a century, this “nuclein” was a chemical curiosity whose profound importance went completely unrecognized — a reminder that discovering a thing and understanding it can be separated by generations.

An Unlikely Source

In the late nineteenth century, Friedrich Miescher set out to study the chemistry of white blood cells, which he collected from the pus on discarded surgical bandages. From the nuclei of these cells he isolated a novel substance rich in phosphorus, unlike any protein — a molecule no one had described before. He called it nuclein, for the cell nuclei it came from.

A Discovery Ahead of Its Time

Miescher had isolated DNA, but neither he nor his contemporaries grasped what it did. For decades the molecule was regarded as a structural or storage substance, too simple and repetitive, it was thought, to carry the complexity of heredity — a role most assumed belonged to proteins. The molecule of life sat identified but misunderstood for the better part of a century.

The Slow Recognition

Only in the twentieth century did experiments prove that DNA, not protein, is the material of heredity — and only then did Miescher's obscure nuclein reveal itself as the most important molecule in biology. The double helix soon followed, and the substance from the surgical bandages became the foundation of an entire science. Discovery had preceded understanding by generations.

Isolating DNA Today

What Miescher did crudely, laboratories now do routinely: extract and purify DNA from cells for study. A modern extraction yields a solution of DNA whose concentration is measured, and multiplying concentration by volume gives the total amount recovered — the practical descendant of the first isolation of the molecule no one, at the time, could imagine the importance of.

Calculating Yield

To convert concentration and volume into total DNA yield, use the DNA Extraction Yield Calculator. Weigh the DNA with the DNA Molecular Weight Calculator, and total a genome's content with the Ploidy DNA Content Calculator.