The language of genes has become common parlance. We know they make your eyes blue, your hair curly or your nose straight. Newspapers tell us that our genes control our risks of cancer, heart disease, alcoholism or Alzheimer’s. Six hundred pounds will buy you your very own genome readout, neatly stored on a USB stick. And advances in genetic medicine hold huge promise.So we’ve all heard of genes, but how do they actually work ?There is 2.2 metres of DNA inside every one of your cells; this encodes more than 20,000 genes, tangled into a mass of molecular spaghetti. This is the text of the cook-book of life, and hidden in these strands are the instructions that tell cells when and where to turn genes on or off.In 1935, Ernest Hemingway was given Snowball, a six-toed cat who went on to father a line of moggies bearing this distinctive genetic marker that still roam the writer’s Florida ranch. Scientists now know that the fault driving this profusion of digits lies in a tiny genetic control switch, miles away (in molecular terms) from the gene that ‘makes’ toes. Researchers are discovering more about the myriad molecular switches that make sure genes are turned on at the right time and in the right place, and what happens when they don’t. This is allowing a four-dimensional picture of DNA to be built - a dynamic, writhing biological library, rather than static strings of genetic code.Drawing on stories ranging from six-toed cats to fish hips, werewolves and zombie genes, geneticist Kat Arney explores how DNA is packed, unpacked and read, creating a companion reader to the book of life itself.
