INTRODUCTION

Jonathan Weitzman & Matthew Weitzman

Few scientific disciplines have captured the human imagination like the field of genetics. Perhaps we are fascinated by it because it tackles questions at the very essence of who we are and what gives each of us our personal identities: What explains why we look like our parents? What makes us different from our brothers and neighbours? And what will we pass on to the next generation? These questions are as old as humankind, but a century ago a science was born that would provide unexpected insights, make unprecedented progress and challenge the ways we think about heredity.

The twentieth century was a whirlwind roller coaster ride, with biomedical promises and ethical challenges at every turn. The painstaking observations of Gregor Mendel allowed him to define some basic rules for the inheritance of characteristics (or traits). The rediscovery of his work at the turn of the century set the stage for exploring what is transmitted from one generation to another and how traits are determined. This new science would require new words to describe it. The British biologist William Bateson coined the term ‘genetics’ (from the Greek ‘to give birth’) to describe this new science of heredity in a personal letter in 1905 and then a year later publicly at the Third International Conference on Plant Hybridization in London. Soon the words ‘gene’ and ‘genome’, ‘genotype’ and ‘phenotype’ were born. Strong personalities abounded in this new field, all keen to uncover the mysteries of heredity. There would be moments of great achievement, like the ingenious cracking of the genetic code, or the discovery of the double helix – the beautifully simple structure of the DNA molecule that would become an icon. The twentieth century closed with one of the most exciting challenges in modern biology: a race, comparable to the race to put man on the Moon. Never before had so many geneticists from around the world worked together on a project with such scope and ambition. The international Human Genome Project set out to decrypt the three billion letters that make up the human genome – the Book of Life!

There is no area of biology that has not been profoundly impacted by modern genetics. Much of the progress in the field was due to the extraordinary speed with which new technologies emerged to address challenges. The realization that the way DNA and genes work is the same across the animal and plant kingdoms opened the door to a menagerie of experimental modelling systems. Discoveries in single-celled bacteria, the common baker’s yeast or the lowly fruit fly provided clues to the underlying rules of genetics. Indeed, the functions of pieces of DNA could be tested by transferring genes from one organism to another. Researchers learned how to sequence, copy, synthesize and engineer DNA molecules, often exploiting the machines (or enzymes) that Nature herself had taken millennia to perfect. This extraordinary progress led to breakthroughs in understanding human diseases and the promise of a new type of genetic medicine. But the promises also brought fears and inspired macabre fiction and fantasies.

Progress continues at a breathtaking pace. Human genomes are being sequenced in their thousands, gene therapy is finally correcting errors to save peoples’ lives and gene editing has reached unprecedented levels of precision. The field of genetics has moved from an esoteric science of abstract concepts, to a series of technologies that will impact our daily lives. In this book we set out to share our excitement at this wonderful adventure and to demystify the science that sometimes hides behind its jargon. The words ‘gene’ and ‘DNA’ have crept into our everyday speech, but it is often unclear what they really mean. It is important to explain what genetics can and cannot say about who we are. The molecules and the enzyme machines that copy, interpret and protect our genomes are all microscopic, but their impact on society is gigantic and in 30-Second Genetics we want to equip general readers to participate in the debate about how genetics and genetic information will be used by society and by generations to come.

About this book

In 30-Second Genetics experts from around the globe guide us through the jargon of modern genetics from gene to genome, from the deciphering of the genetic code to the sequencing of the human genome. Here specialists demystify the terms and the concepts, and make us wonder at how much we have learned about genetics and how much we still have to discover. 30-Second Genetics presents each topic in a clear and concise single page. The main paragraph, the 30-Second Theory, is complemented by the 3-Second Thrash, which gives a quicker overview – the key facts in a single sentence. And the 3-Minute Thought fleshes this out, adding intriguing aspects of the subject. Each chapter also contains the biography of a pioneer in the field – the men and women who contributed to our understanding of modern genetics. The book begins with a presentation of the historical and conceptual foundations of this new science. It then plunges into the details, first by explaining the roles of chromosomes and cells through to the level of genes and genomes, before discussing the emerging field of epigenetics, which studies genetic effects that are not encoded in the DNA sequence of an organism. The health and disease chapter places these molecular events in the context of physiology and the bodily processes that are associated with disease. No discussion of genetics would be complete without a description of the progress in technologies and experimental approaches. The book ends with some predictions of how these technologies might impact our lives and medicine in the near future.