This week in history: The structure of DNA discovered

It has long been known that traits in animals and plants pass down the generations. Until recent decades, we had little idea of exactly how.

In 1866, Austrian monk Gregor Mendel wrote a paper outlining a framework for how inheritance takes place. His work with peas showed that traits are passed on in a discrete way and in distinct patterns: ie, that offspring don’t inherit a simple blend of their parents’ traits. Ignored or rejected at the time, his theories are fully accepted now.

Shortly after Mendel’s work, Swiss doctor Friedrich Miescher isolated a molecule (nucleic acid) from the nuclei of white blood cells. But the chemical’s significance wasn’t known until 1944, when Oswald Avery discovered that nucleic acid (DNA) had a role in inheritance. How it worked remained a mystery.

In 1953, James Watson and Francis Crick, working on X-rays of DNA crystals produced by Rosalind Franklin, deduced that the molecule must have a ‘double helix’ structure. This immediately suggested how inheritance might work, as Watson and Crick hinted in their paper.

Later research has confirmed their hunches, leading to the creation of whole new industries. In 1976, for example, Herbert Boyer founded Genentech, one of the first biotechnology companies, which was bought in 2009 by pharmaceutical giant Roche for $46.8bn.

Technology has now reached the point where we can ‘read’ DNA strands rapidly to understand the genetic basis of many things, including diseases. Genetic modification is now behind everything from synthetically produced insulin for diabetics to genetically modified crops.