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Schaum's Outline of Genetics SCHAUM’S outlines Genetics This page intentionally left blank SCHAUM’S outlines Genetics Fifth Edition Susan L. Elrod, Ph.D. Professor of Biological Sciences California Polytechnic State University at San Luis Obispo William D. Stansfield, Ph.D. Emeritus Professor of Biological Sciences California Polytechnic State University at San Luis Obispo Schaum’s Outline Series New York Chicago San Francisco Lisbon London Madrid Mexico City Milan New Delhi San Juan Seoul Singapore Sydney Toronto SUSAN L. ELROD has degrees in Biological Sciences from California State University, Chico (B.S., 1986) and Genetics from the University of California, Davis (Ph.D., 1995). Graduate work was followed by a Postdoctoral Fellowship at Novozymes Biotech, Inc., in Davis, California. Her research is focused on the molecular genetics of yeast and filamentous fungal systems, with a particular interest in industrial and environmental applications. She holds three patents and has published in the area of gene cloning and protein expression in Aspergillus oryzae. She has been Professor in the Biological Sciences Department at California Polytechnic State University, San Luis Obispo, since 1997, where she teaches introductory and advanced Genetics, and is Director of the university Center for Excellence in Science and Mathematics Education. WILLIAM D. STANSFIELD has degrees in Agriculture (B.S., 1952), Education (M.A., 1960), and Genetics (M.S., 1962; Ph.D., 1963; University of California at Davis). His published research is in immunogenetics, twinning, and mouse genetics. From 1957 to 1959 he was an instructor in high school. He was a faculty member of the Biological Sciences Department of California Polytechnic State University from 1963 to 1992 and is now Emeritus Professor. He has written university-level textbooks in evolution and serology/immunology, and has coauthored a dictionary of genetics. Copyright © 2010, 2002, 1991, 1983, 1969 by The McGraw-Hill Companies, Inc. All rights reserved. Except as permitted under the United States Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of the publisher. ISBN: 978-0-07-162504-3 MHID: 0-07-162504-6 The material in this eBook also appears in the print version of this title: ISBN: 978-0-07-162503-6, MHID: 0-07-162503-8. All trademarks are trademarks of their respective owners. Rather than put a trademark symbol after every occurrence of a trademarked name, we use names in an editorial fashion only, and to the benefit of the trademark owner, with no intention of infringement of the trademark. Where such designations appear in this book, they have been printed with initial caps. McGraw-Hill eBooks are available at special quantity discounts to use as premiums and sales promotions, or for use in corporate training programs. To contact a representative please e-mail us at [email protected]. TERMS OF USE This is a copyrighted work and The McGraw-Hill Companies, Inc. (“McGraw-Hill”) and its licensors reserve all rights in and to the work. Use of this work is subject to these terms. Except as permitted under the Copyright Act of 1976 and the right to store and retrieve one copy of the work, you may not decompile, disassemble, reverse engineer, reproduce, modify, create derivative works based upon, transmit, distribute, disseminate, sell, publish or sublicense the work or any part of it without McGraw-Hill’s prior consent. You may use the work for your own noncommercial and personal use; any other use of the work is strictly prohibited. Your right to use the work may be terminated if you fail to comply with these terms. THE WORK IS PROVIDED “AS IS.” McGRAW-HILL AND ITS LICENSORS MAKE NO GUARANTEES OR WARRANTIES AS TO THE ACCURACY, ADEQUACY OR COMPLETENESS OF OR RESULTS TO BE OBTAINED FROM USING THE WORK, INCLUDING ANY INFORMATION THAT CAN BE ACCESSED THROUGH THE WORK VIA HYPERLINK OR OTHERWISE, AND EXPRESSLY DISCLAIM ANY WARRANTY, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. McGraw-Hill and its licensors do not warrant or guarantee that the functions contained in the work will meet your requirements or that its operation will be uninterrupted or error free. Neither McGraw-Hill nor its licensors shall be liable to you or anyone else for any inaccuracy, error or omission, regardless of cause, in the work or for any damages resulting therefrom. McGraw-Hill has no responsibility for the content of any information accessed through the work. Under no circumstances shall McGraw-Hill and/or its licensors be liable for any indirect, incidental, special, punitive, consequential or similar damages that result from the use of or inability to use the work, even if any of them has been advised of the possibility of such damages. This limitation of liability shall apply to any claim or cause whatsoever whether such claim or cause arises in contract, tort or otherwise. Preface The Fifth Edition of Schaum’s Outline of Genetics comes at an exciting time in our history. The Human Genome Project was completed in 2003, bringing with it new understanding as well as new questions about the structure and function of our genetic material. We are gaining significant insight into a variety of human diseases and conditions, from Alzheimer’s disease to obesity. As it turns out, one of the biggest challenges has been to determine the precise number of protein-coding genes in the human genome. While there is much research and debate on this topic, the exact number is not yet known. Estimates range from 20,000 to 30,000 and the discovery process has, in some senses, led to a gene identity crisis. The gene is a complex genetic entity, for which a simple definition no longer exists. While some might assert that it is the coding sequence of a gene that defines it, it is difficult to precisely map where coding sequences begin and end at the molecular level, and many overlap. The growing role of RNA in regulating and even in rewriting genomic sequences is challenging many of our assumptions about the primacy of DNA as the sole guardian of heredity. The central idea of genes as carriers of protein information is also being challenged; in fact, there may be more genes that code for important RNA molecules. The field of genetics is one of the most rapidly growing fields in science, with the fields of genomics and bioinformatics probably growing the fastest. With the advent of new DNA sequencing technologies, we are generating more sequence information than we have computing power to analyze. New technologies are leading to pioneering projects, such as The HapMap, a project aimed at identifying the variation among individual human genomes in order to better understand disease and its treatment, as well as our ancestral origins. There are also now several companies that offer individuals the opportunity to learn about the DNA markers within their own genomes that may indicate propensities to certain diseases and disorders. The new frontier of personalized genomics and medicine is a dual-edged sword with detailed genetic information on one side and prickly issues of ethics and human welfare on the other. To reflect this growing knowledge, this new edition contains updated content in several chapters, particularly those dealing with molecular biology and genomics. While this book has traditionally been viewed primarily as a supplement to help student’s solve problems and pass exams, it contains as much content as might be covered in a one-quarter or a one-semester introductory course when serving as the only course textbook. We also view it as a helpful study tool for people taking graduate and medical school entrance exams, and the new content reflects this emphasis as well. We hope you find this new edition readable, useful and even enjoyable. S. L. ELROD W. D. STANSFIELD San Luis Obispo, California June 2, 2009 v This page intentionally left blank Contents CHAPTER 1 The Physical Basis of Heredity 1 1.1 Genetics 1.2 Cells 1.3 Chromosomes 1.4 Cell Division and Reproduction 1.5 Mendels Laws of Inheritance 1.6 Gametogenesis 1.7 Genetic Model Systems CHAPTER 2 Patterns of Inheritance 23 2.1 Terminology 2.2 Dominant and Recessive Alleles 2.3 Crosses Involving Single Genes 2.4 Other Allelic Relationships 2.5 Probability Theory 2.6 Statistical Distributions 2.7 Crosses Involving Two or More Genes 2.8 Testing Genetic Ratios 2.9 Pedigree Analysis CHAPTER 3 The Biochemical Basis of Heredity 65 3.1 Nucleic Acids 3.2 Protein Structure 3.3 Genetic Information Flow 3.4 Defining the Gene 3.5 Protein Synthesis 3.6 DNA Replication 3.7 Mutations 3.8 DNA Repair CHAPTER 4 Genetic Interactions 97 4.1 Two-Factor Interactions 4.2 Epistatic Interactions 4.3 Pedigree Analysis 4.4 Nonepistatic Interactions 4.5 Interactions with Three or More Factors 4.6 Pleiotropism CHAPTER 5 The Genetics of Sex 116 5.1 The Importance of Sex 5.2 Sex-Determining Mechanisms 5.3 Sex-Linked Inheritance 5.4 Variations of Sex Linkage 5.5 Sex-Influenced Traits 5.6 Sex-Limited Traits 5.7 Sex Reversal 5.8 Sexual Phenomena in Plants CHAPTER 6 Linkage and Chromosome Mapping 142 6.1 Recombination Among Linked Genes 6.2 Genetic Mapping 6.3 Linkage Estimates from F2 Data 6.4 Use of Genetic Maps 6.5 Crossover Suppression 6.6 Tetrad Analysis in Fungi 6.7 Recombination Mapping with Tetrads CHAPTER 7 Cytogenetics 182 7.1 The Union of Cytology with Genetics 7.2 Chromosome Structure 7.3 Variation in Chromosome Number 7.4 Variation in Chromosome Size 7.5 Variation in the Arrangement of Chromosome Segments 7.6 Variation in the Number of Chromosome Segments 7.7 Variation in Chromosome Morphology 7.8 Human Cytogenetics vii viii Contents CHAPTER 8 Quantitative Genetics 212 8.1 Qualitative vs.
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