The Double Helix

To understand the amazing significance of James Watson’s story, it’s important to understand what makes DNA so important.

Deoxyribonucleic acid, or DNA, is a molecule containing our fundamental genetic information, and it’s made up of two strands of sugar-phosphate that twist around each other like the railings of a spiral staircase.

This structure is called a double helix. Since a single helix would resemble a coiled spring, a double helix is basically two springs curling in synchronicity with one another. These two strands are connected to bases, much like the railings on a spiral staircase are connected to steps. And each base is made of two out of four genetic building blocks, which are abbreviated with the letters A, C, T or G.

Whenever our cells replicate, the information in our DNA is copied and passed on. But for a long time, scientists wondered how this process could repeat itself millions of times, with very few errors.

The answer became clear when the double helix was discovered: when a cell splits, the staircase divides right down the middle. It works perfectly since the bases that connect the two strands can only bind with other specific bases. So when the two strands are split down the middle, each one becomes an inverted copy of the other. Once separated, the two strands act like a template for making two new double helixes.

It’s a beautifully simple and dependable process, and it even helped confirm Darwin's theory that all life has a common ancestor.

This happened in 1961, eight years after the discovery of the double helix, when Francis Crick, Watson’s DNA research partner, led an experiment that revealed the nature of the genetic code. It showed how the letters in three of the DNA bases serve as the code for one amino acid, which in turn can be linked to form a genetic code that describes the form and function of an individual’s body.

And not just human bodies. The genetic code showed us that all organisms, including plants and animals, share the same primordial beginnings.

But, we are getting ahead of ourselves. Let’s go back and look at how the double helix structure of DNA was discovered.