Our scalp cells sprout hair while the cells lining our nose and lungs make mucus. Our fat cells bloat, our retinal cells turn light into electricity, and our heart cells contract to order. Yet every one of these cells comes equipped with exactly the same genes. How can such variety come from one genome? "The important thing is not just what genes you have, but what you do with them," says Bryan Turner, a geneticist from the University of Birmingham in Britain. Each kind of cell must be following an instruction book that tells it how to read DNA's genetic blueprint in its own special way. But where is this instruction book? What is in charge of the genetic code?
展开▼
