Francis Crick and James Watson: And the Building Blocks of Life Edward Edelson Oxford University Press Francis Crick and James Watson And the Building Blocks of Life Image Not Available XFORD PORTRAITS INSCIENCE Owen Gingerich General Editor Francis Crick and James Watson And the Building Blocks of Life Edward Edelson Oxford University Press New York • Oxford Fondly dedicated to Hannah, the newest member of the family. Oxford University Press Oxford New York Athens Auckland Bangkok Bogotá Bombay Buenos Aires Calcutta Cape Town Dar es Salaam Delhi Florence Hong Kong Istanbul Karachi Kuala Lumpur Madras Madrid Melbourne Mexico City Nairobi Paris Singapore Taipei Tokyo Toronto Warsaw and associated companies in Berlin Ibadan Copyright © 1998 by Edward Edelson Published by Oxford University Press, Inc., 198 Madison Avenue, New York, New York 10016 Oxford is a registered trademark of Oxford University Press All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of Oxford University Press. Design: Design Oasis Layout: Leonard Levitsky Picture research: Lisa Kirchner Library of Congress Cataloging-in-Publication Data Edelson, Edward James Watson and Francis Crick and the building blocks of life / Edward Edelson. p. c. — (Oxford portraits in science) Includes bibliographical references and index. ISBN 0-19-511451-5 (library edition) 1. Watson, James D., 1928– —Juvenile literature. 2. Crick, Francis, 1916– —Juvenile literature. 3. DNA—Research—Juvenile literature. 4. Molecular biolo- gists—Biography—Juvenile literature. [1.Watson, James D., 1928– . 2. Crick, Francis, 1916– . 3. Molecular biologists. 4. DNA—Research.] I. Title. II. Series. QP624.E34 1998 572.8’6’072—dc21 97-42791 CIP AC 9 8 7 6 5 4 3 2 1 Printed in the United States of America on acid-free paper On the cover: Francis Crick and James Watson in 1993; Inset: Watson and Crick in 1953. Frontispiece: Watson and Francis at the Cavendish Laboratory at Cambridge University in 1953. Contents Chapter 1. A Story of Two Men and a New Science . .8 Chapter 2. Dr. Watson Meets Mr. Crick . .14 Chapter 3. The Road to DNA . .26 Sidebar: Mendelian Genetics . .33 Chapter 4. The Emergence of Nucleic Acids . .36 Sidebar: The Waring Blendor . .49 Chapter 5. The Emergence of the Double Helix . .50 Chapter 6. How DNA Works . .70 Sidebar: Solving the Sickle-Cell Puzzle . .88 Chapter 7. Watson and the Human Genome Project . .90 Sidebar: The First Cloned Mammals . .102 Chronology . .104 Further Reading . .106 Index . .108 This page intentionally left blank XFORD PORTRAITS INSCIENCE Charles Babbage Alexander Graham Bell Nicolaus Copernicus Francis Crick & James Watson Marie Curie Charles Darwin Thomas Edison Albert Einstein Michael Faraday Enrico Fermi Benjamin Franklin Sigmund Freud Galileo Galilei William Harvey Joseph Henry Edward Jenner Johannes Kepler Othniel Charles Marsh & Edward Drinker Cope Margaret Mead Gregor Mendel Isaac Newton Louis Pasteur Linus Pauling Ivan Pavlov Ernest Rutherford Image Not Available CHAPTER 1 A Story of Two Men and a New Science This is an unusual biography, in several ways. First, it is the biography of two people, not one. The names of James Watson and Francis Crick are bound together forever. You cannot mention Watson without mentioning Crick, because the discovery they made about the molecule of life was truly a joint enterprise. (Years after the discovery, Crick recalled introducing Watson to someone at the laboratory where Crick was working. “Watson?” the person said in surprise. “I thought your name was Watson-Crick.”) This story is also unusual because the heart of their nar- rative and the discovery they achieved covers just a few years rather than a lifetime. After that achievement, they went on to do distinguished work separately and rarely worked together again. But it is the one finding that they reported in 1953 that put their names indelibly in the histo- Francis Crick and James Watson in 1993, at the ry book of science. What they discovered was the secret of 40th anniversary celebra- life, in molecular form. They were the first to describe the tion of the publication of structure of deoxyribonucleic acid, DNA, the molecule their historic Nature that carries the information of life. magazine article, in which they described the An information-carrying segment of DNA is called a molecular structure of gene. Genes determine the basic nature of all living things, DNA for the first time. 9 Francis Crick and James Watson including humans, and so DNA is considered the most important molecule of life. Specifically, genes carry the information for the production of proteins, the molecules that make up most of the body. When Watson and Crick described the structure of DNA, they thus opened the door to a new science of genetics—and, beyond that, the science of molecular biology—a field that is still growing and devel- oping, and one that is having an increasing influence on medicine and on all of biology. The names and work of many other scientists are an essential part of this story. Some of those scientists set the stage for what Watson and Crick accomplished. Some were competitors in a race to accomplish what Watson and Crick were the first to achieve. Others joined Watson and Crick to build on the DNA discovery—first to decode the genetic message carried in that molecule, then to show how infor- mation is transferred from DNA (correctly or incorrectly) to govern the production of proteins and thus to shape liv- ing things. And since this is a story of modern science, the actors in it were from a number of countries and moved around frequently, attending a variety of meetings and mov- ing from one laboratory to another, and often from country to country. Finally, the full consequences of what Watson and Crick discovered are still being explored. Theirs is a story that began more than 40 years ago, is still being told, and has implications that will extend well into the 21st century. One example of this ongoing effort is the Human Genome Project, a program to make a map of the entire human genetic apparatus, called the genome; to identify all the genes that make us what we are; and to find the complete sequence of subunits within the genome. In addition to its basic scientific value, this information can be used to detect and help treat young people and unborn children with inher- ited genetic diseases. It can also identify adults at high risk of diseases such as breast cancer, in which individual genes play a 10 A Story of Two Men and a New Science role—an effort that has already begun. Watson helped the Human Genome Project get off to a good start, serving as its director during the critical early years. Researchers building on the work done by Watson and Crick have established the technique in which genes can be manipulated and transferred. Recombinant DNA technolo- gy has become both a new industry and a new medical field. Proteins used in medicine, such as insulin and human growth hormone, are produced by genetic engineering— the process of putting the appropriate genes into corre- sponding bacteria, which then turn out large amounts of the medicinal protein. The same genetic technology is also being used in agriculture, to develop species of plants that are resistant to attack by insects and other predators, to increase production of milk and crops, and to make flowers with new colors and patterns. And now it has even become possible to clone mammals and other animals, creating exact genetic copies of individual animals by transferring DNA from one cell to another. Genetic technology is also being used in medicine, to treat genetic diseases by giving patients normal genes to replace flawed genes causing serious problems. The first attempt at human gene therapy took place in 1990. Researchers at a National Institutes of Health facility treated a young girl with a deficiency in her immune system that prevented her from responding normally to fight off infec- tious agents such as disease-causing bacteria. They gave her 1 billion immune system cells that had been genetically engineered to provide the protection she lacked. A number of other gene therapy trials have been made since then, and the field is growing. The subject of all this work is the cell, the smallest unit of living things. The body is made up of billions of cells, each with a specialized purpose. A brain cell is different from a skin cell, which is different from a muscle cell, and so on. Cells are very small, invisible to the naked eye. A sin- 11 Francis Crick and James Watson The first X-ray diffraction photograph of a stretched, dried film of DNA. X-ray diffraction photos were used to determine the three- dimensional structure of biological molecules. Image Not Available gle freckle on the back of your hand, for example, contains several thousand cells. Under a high-powered microscope, cells show two kinds of basic internal structure. Most of the cells in the human body, for example, consist mainly of a large segment called the cytoplasm, at the center of which is a small unit called a nucleus. It is the nucleus that contains DNA, the genetic material. Within the nucleus are chromosomes— furled, stringlike bodies that are made up of DNA and thus contain the genes. The nucleus also holds the cellular machinery for activating the information contained in the genes and for reproducing the chromosomes. If you could take all the chromosomes out of one cell and unfurl them, they would stretch about six feet in length.