Two centuries ago, nobody knew much about what made a single fertilised cell grow into a human. Or – for that matter – a dog, a sea urchin, a worm or a whale. The problem was nobody could imagine how a microscopic bag of chemicals could possibly split in half again and again, yet still have enough information to make all the different organs and tissues in the body.
Since the invention of the microscope, scientists have known many cells contain a round, dark nucleus. In the late 19th century, a Swiss physician managed to extract specific chemicals from the nucleus that he called nuclein.
Bit by bit, over the following decades, chemists worked out what was in this goopy material. There were hints that these chemicals could hold the key to what turns a simple cell into a complex organism. Finding convincing evidence took a long time.
The chemicals are acids, so they became known as nucleic acids. Then scientists found different types of chemicals that were described as bases – including adenine, thymine, guanine and cytosine. It was later discovered that they were all linked in chains.
In the early 1940s, a physicist by the name of Erwin Schrödinger gave lectures on life. He imagined a chemical with repeating units varied enough to code information. The talks were inspirational.
The pieces were coming together. Deoxyribonucleic acid (DNA) is passed from one generation to the next, carrying information telling the cell how to grow and change.
In 1953, two names became famously linked with DNA – James Watson and Francis Crick. Using an X-ray image prepared by a physicist named Rosalind Franklin, they calculated the structure of the nucleic acid. The result was the familiar twisting ladder of the double helix.
The story doesn’t end there. Even today, we’re still learning how DNA molecules change shape, combine with other chemicals and transform our cells.
Learning about DNA can seem rather daunting. To make it a little easier, we’ve developed a game. The goal is simple: competing against a partner, draw base cards from a pile, and arrange them according to a sequence. To make things a little more challenging, there are action cards that could help you, or help your competitor.
To play the Double Helix card game, download the cards and the instructions and print them out. If you don’t like the rules, don’t worry – the game is simple enough, you can change them to make up your own game. Feel free to share your own rules in the comments!
Maybe with some practise, one day you’ll make your own DNA discovery.