brown85 - The Impact of Modern Genetics D ONALD D. B ROWN T...

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The Impact of Modern Genetics DONALD D. BROWN T HE T ANNER LECTURES ON H UMAN V ALUES Delivered at Brasenose College, Oxford University May 15 and 16, 1984
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D ONALD D. B ROWN was born in Cincinnati, Ohio, in 1931, and educated at Dartmouth College and the Uni- versity of Chicago, where he received an M.D. degree. After an internship in New Orleans, he served two years as a commissioned officer in the U.S. Public Health Service at the National Institutes of Health, doing full-time research. He went to the Pasteur Insti- tute in Paris for a year before joining the Department of Embryology of the Carnegie Institution of Washing- ton, where he began as a postdoctoral fellow, became a Staff Member in 1962 and Director in 1976. Dr. Brown is now a Professor in the Department of Biology of the Johns Hopkins University. He has received several awards and honorary degrees and has been honored by election to the National Academy of Science, the Amer- ican Academy of Arts and Sciences, and the American Philosophical Society. He has written about one hun- dred scientific papers.
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I. GENETIC ENGINEERING: ITS PROMISE AND PROBLEMS The discovery of the double helical structure of DNA in 1953 has played a role in modern genetics analogous to the impact that the discovery of the atom had for nuclear physics during the first half of this century. Prior to 1953, genes were defined as elements that obeyed the well-known Mendelian rules of heredity. A defec- tive gene was often recognized by a change in some visible trait. Among the earliest known examples of genes that obey Mendel’s laws are those whose mutations cause certain diseases such as hemophilia and sickle cell anemia. It has been known for a long time that the occurrence of these diseases in affected families is predictable. The advent of genetic chemistry made us consider for the first time how the DNA molecule could encode such complex traits. Discoveries since 1953 have taught us how to work with the genetic material as a chemical reagent. We have learned about the structure of DNA and its chemistry. This information explains well-known biological functions of genes such as their ability to reproduce themselves exactly and how information is encoded and expressed by genes. It is not possible to talk reasonably about the impact of these discoveries without understanding something about the science of genetic biochemistry. I propose to explain it as briefly as possible before evaluating the risks and benefits of genetic engineering. Genetic biochemistry DNA has two important functions that it must carry out in liv- ing cells. It duplicates itself, and it encodes protein. Inherent in the structure of DNA are explanations for both functions. [77]
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78 The Tanner Lectures on Human Values DNA consists of four building blocks called nucleotides or “bases,” designated by the letters A, G, C, and T, that are linked together to form very long molecules. Two of these long chains are intertwined to form a double helix. The key rule used by
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This note was uploaded on 01/16/2012 for the course BI 200 taught by Professor Potter during the Fall '11 term at Montgomery College.

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brown85 - The Impact of Modern Genetics D ONALD D. B ROWN T...

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