Über die Autorin bzw. den Autor

Richard V. Kowles, PhD (Winona, MN), is Distinguished University Professor Emeritus in Biology at Saint Mary’s University of Minnesota. He is the author of Solving Problems in Genetics and Genetics, Society, and Decisions, among other publications.

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THE WONDER OF GENETICS

Prometheus Books

Contents

Preface.................................................................91. Introduction—Genetics Everywhere...............................132. Males and Females—There Are Differences........................193. Females Are Genetic Mosaics..........................................274. Anyone Exactly Like You?.............................................335. Playing Genetic Roulette.............................................416. The Importance of Mama...............................................497. Those Awful Sideshows................................................578. Why So Many Miscarriages?............................................619. Radiation—Friend or Foe?.......................................7110. You Are What You Eat—Rearranged...............................8311. Women in the Olympics...............................................9312. Marrying Your Cousin................................................9713. The Baby Is Not Mine................................................10514. Losing Their Punch..................................................11515. Genetics Is Big in Agriculture......................................12316. Amazing Maize.......................................................12917. Seedless Watermelons................................................13518. Eating Genetically Modified Foods...................................13919. Growing Human Hormones on the South 40..............................14720. Gene Therapy—Changing Your Heredity...........................15721. Animals Have Stem Cells Too.........................................16322. Sterile? So What!...................................................16723. Cloning—Chip Off the Old Block................................17524. An Old Conflict—Nature versus Nurture.........................18525. The Bad Seed........................................................20126. Catching Bad People and Freeing Innocent People.....................20727. Free Will or Not....................................................21528. Cancer—Innocent Cells Gone Astray.............................22129. Human Genome Project................................................23130. Skin Color..........................................................24531. Gene Pools and Race.................................................25132. Fountain of Youth...................................................26133. The Discord between Evolution and Creationism.......................27134. Movies and Genetic Implications.....................................27935. Genetic Misconceptions..............................................28536. Genetics and Politics Crossing Paths................................29537. Conclusions.........................................................303Glossary................................................................307Index...................................................................331

Chapter One

What factors contribute to make us what we are? Why are we male or female, short or tall, blonde or brunette, blue-eyed or brown-eyed? Why do we sometimes resemble our parents, siblings, aunts, or uncles? Why do we sometimes not resemble any of our relatives? Why are some people born with defects in anatomy (such as extra fingers), defects of biochemistry (such as the inability to metabolize the amino acid phenylketonuria), or defects of neural function (such as manic depression)?

Researchers in the field of genetics investigate all of these questions, and more. All living organisms, no matter how primitive or complex, are the result of the workings of genetics. Living organ isms are composed of lifeless molecules. These molecules conform to all of the physical and chemical laws that describe inanimate matter. Yet living organisms possess extraordinary attributes not shown by inanimate matter. Living organisms have molecular organization, and these molecules have very specific functions. Living organisms can extract and transform energy from the environment. Living organisms have self-replication. If living organisms are composed of molecules that are intrinsically inanimate, why then does living matter differ so drastically from other matter? The answer lies in living organisms being able to replicate their genes. These units of inheritance, the genes, hold the information necessary to direct the construction of enzymes that are the protein tools active in cellular reactions and absolutely essential for life itself. These processes are the essence of genetics.

Genetics is a fascinating science dealing with the inheritance of physical and chemical characteristics. More specifically, genetics is the discipline involved in the study of variation due to heredity and the effects of environment on this variation. Heredity is the overall process of transmitting traits from parents to offspring. In other words, heredity is the tendency to be like your parents. To a large sigh of relief for some, "tendency" only means "tendency."

Almost everyone agrees that the actual birth of genetics came about with Gregor Mendel, an Austrian monk. Mendel devoted years to a study of several hereditary traits, or characters, that he observed in common garden peas. His classic paper explaining his plant hybridization experiments first appeared in journal form in 1866, although no one gave his results serious attention at that time. Mendel collected a large amount of data indicating that hereditary characteristics were due to particles of some kind. He called these particles "factors" and showed that they passed from one generation to the next according to predictable patterns. He further observed that definitive hereditary characteristics (such as short or tall peas) did not blend together into an average form (such as medium-height peas). The characteristics remained in their original form, generation after generation.

Many students of the history of genetics, however, see 1900 as the true birth date of genetics, for it was then that three biologists independently rediscovered Mendel's paper. As a result, the basic laws of heredity became known, and studies of them could then progress at a rapid pace. Yet traditional biologists were slow to accept studies of heredity as a distinct discipline. William Bateson named the field "genetics" in 1905, and it became a respectable science about 1910.

During the period from 1900 to 1910, scientists made significant contributions to genetics. In 1903, W S. Sutton and T. Boveri independently and concurrently made the correlation between the pat tern of inheritance of Mendel's factors and the behavior of chromosomes in cells. They concluded that chromosomes were the vehicles carrying these hereditary particles. William Bateson and R. C. Punnett, among others, conducted many plant hybridization experiments during this time, again with peas but with other organisms too. These researchers quickly learned that heredity was certainly more complicated than Mendel had thought. In most cases, they supported the independence of two gene pairs in cell division as set forth by Mendel, but they discovered at the same time that exceptions occurred.

By 1911, the fruit fly (Drosophila) had become a...