Solving Problems in

Genetics

Springer Science+ Business Media, LLC

Solving Problems in

Genetics

Richard Kowles

With 266 Figures

Springer

Richard Kowles Department of Biology Saint Mary's University of Minnesota 700 T errace Heights Winona, MN 55987-1399 USA

library of Congress Cataloging-in-Publication Data Kowles, Richard V.

Solving problems in genetics/Richard Kowles. p. cm.

Inc\udes bibliographical references and index. ISBN 978-0-387-98841-2 ISBN 978-1-4613-0205-6 (eBook)

DOI 10.1007/978-1-4613-0205-6 1. Cenetics-Problems, exercises, etc. 1. Title.

QH440.3 .K69 2000 576.5'076---dc21

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© 2001 Springer Science+Business Media New York Originally published by Springer-Verlag New York, Ine. in 2001 Softcover reprint of the hardcover lst edition 2001 AII rights reserved. This work may not be translated or copied in whole or in part without the written permission of the Springer Science+Business Media, LLC, except for brief excerpts in connection with reviews of scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use of general descriptive names, trade names, trademarks, etc., in this publication, even if the former are not especially identified, is not to be taken as a sign that such names, as understood by the Trade Marks and Merchandise Marks Act, may accordingly be used freely byanyone.

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ISBN 978-0-387-98841-2 SPIN 10725181 (hardcover) SPIN 10725042 (softcover)

Dedication

Rose

Deb

[J Elizabeth Reed Dylan Maxwell

Preface

Genetics is largely an analytical science. Techniques of analysis are an important

dimension of genetics. The development of the discipline has been staggering

in recent years, but the basic mechanics of genetics should not be neglected.

Many instructors of genetics agree that students tend to have difficulty con­

ducting genetic analysis. The sole objective of this book is to make students

more adept in the analysis of genetic problems. The book is meant to be sup­

plemental and useful to students of genetics regardless of the textbook being

used in their course. The supplemental, and often complemental, material will

show applications of the concepts explained in genetics textbooks. Some instruc­

tors, however, may want to use the book as their textbook, which would depend

upon the structure and nature of their courses. Students who learn how to manage

genetics problems will better understand the basic principles of genetics and will

vii

Preface

viii

know how to more effectively apply the information to other related genetic

situations.

The book is intended to be used by undergraduate college students ma­

joring in biology and studying introductory genetics. The biology curricula of

many colleges and universities now follow their introductory genetics course

with one or more additional courses that heavily focus on the many recent ad­

vances of molecular biology. This book has several chapters relating to molecular

genetics, but the main objective is to present a broad coverage of genetics.

TopiCS, therefore, concentrate on Mendelian relationships, transmission, cyto­

genetics, molecular, quantitative, and population genetics, with some additional

areas such as maternal inheritance and human genetics. An attempt is made to

present a balanced account of genetics.

The same format is used throughout the entire book. A brief introductory

discussion is provided to set the stage for the ensuing genetic analysis. The

discussion concentrates on genetic analysis, the interpretation of data, and the

explanation of classic experiments. The text material is followed with a relevant

sample and its solution. This format repeats itself throughout each of the chap­

ters. Many related problems are presented at the end of each chapter with their

solutions immediately follOWing that section. The emphasis for both sample

problems and those at the end of the chapters is "solutions" and not just "answers."

Most textbooks, of course, proVide problems and answers. Few will show the

student how to actually solve the problem. Often the student does not have any

idea concerning how the answer was derived. The strategy within this book is

to provide the student with the essential steps and the reasoning involved in

conducting genetic analysis. Although important as other facets of genetics, dis­

cussion and descriptive type questions are not included. Everything is a problem

to be analyzed.

The book is not designed to be read rapidly; rather, it is meant to be

studied in conjunction with the many excellent genetics textbooks available. The

text part of the book contains very few if any embellishments. A deliberate

attempt has been made to make complex concepts simple, and sometimes to

make simple concepts complex. The ruling goal has been to aid the student in

developing analytical ability. Numerous figures and diagrams are included to

promote the goal of making problem solving as student friendly as possible.

In many cases, more than one technique exists to solve genetic problems.

This book offers one variation in solving problems. Some topics and related

problems are included simply for the sake of developing analytical ability; that

is, they are deemed excellent for analysis purposes. Other topics are intentionally

omitted because they are not conducive to the type of analysis preferred in the

book. Much important genetics today centers upon the isolation, cloning, and

sequencing of genes. As imperative as these topics are to a good genetics course,

they do not always lend themselves well to good quantitative-type problems for

students of introductory genetics. This book is not intended to be a compre­

hensive textbook touching upon everything that has happened in the field of

genetics.

The information and accompanying problems tend to build upon each

other; that is, analytical methods learned in early parts of the book are often

subsequently necessary in later analyses. Pedagogically, this adds an element of

recall. Some of the problems are substantial challenges. Instructors mayor may

not assign them, but such problems are sometimes useful for those students who

are not adverse to a good challenge. Instructors can, of course, be selective with

regard to all of the problems. Some topics may not even be used in their course.

Statistical analysis is described at the point of necessity throughout the book.

Additionally, Chapter 12 is highly statistical. Statistical analyses are very im­

portant in the biological sciences and certainly have a solid place in genetics.

They constitute a powerful set of tools, and the discipline lends itself extremely

well to many facets of genetics. Still, many instructors may choose to use only

part of Chapter 12 or completely omit it. Altogether, the book contains 115

sample problems and 317 end of the chapter problems.

Acknowledgments are always in order for such an undertaking. I particu­

larly want to thank Dr. Clare Korte for her many hours of proofreading of the

manuscript and Kate Finley for handling the secretarial details between author

and publisher. Patti Reick proved to be a competent illustrator with a good eye

for detail. Dr. Robin Smith, Executive Editor for Life Sciences at Springer-Verlag

New York, Inc., made the project fun and relatively painless. Also, thanks always

must be given to the reviewers who are so good at detecting what you have

overlooked. And lastly, thanks to the many biology students over the years who

were subjected to many of these problems. They could never resist an oppor­

tunity to inform me of errors and ambiguities.

Richard Kowles

Saint Mary's University of Minnesota

Preface

ix

1 Preface vii

Mendelism

Introduction

Basic Probability: Methods for Analyzing Mendelian Genetics 2

Forked line Method 6

Mendel's Data 8

Crosses Involving Three or More Gene Pairs 10

Goodness of Fit Testing 11

Subdividing Chi Square 15

Gene Interaction 15

Distinguishing Among Genetic Ratios 18

Double Fertilization in Plants 20

Additional Plant Genetics Considerations 22

Contents

xi

Contents

2

3

4

xii

Problems 23

Solutions 28

Reference 38

Sex Determination and Sex Linkage

General Aspects of Mating Systems 39

XXlXY Chromosome System 40

Sex Ratios 40

Binomial Statistics 41

Haploid-Diploid Sex Determination 43

Sex Linkage 44

Pedigrees 47 Partial Sex-Linkage 51

Problems 52

Solutions 56

Chromosomes and Cell Division

Chromosomes 65 The Cell Cycle 66 Further Analysis of the Cell Cycle 68 Percent Labeled Mitoses Method 70

Mitosis 72

Meiosis 75

Genetic Diversity 79 C Values 80

Problems 81

Solutions 86

65

39

Linkage, Recombination, and Mapping

Exceptions to Independent Assortment 93 Recombination Values and Genetic Maps 97 Three-Point Tests tOO

Mapping Concepts 107

Recombination Calculated with F2 Data 111

Haploid Genetics 114

Tetrad Analysis 115

Tetrad Analysis and Gene Mapping 119

Problems 121

Solutions 131

Reference 144

93

5

6

7

Variations in Chromosome Number and Structure

Types of Chromosome Variation 145

Aneuploidy 146

Polyploidy 150

Deletions and Duplications 152

Inversions 156

T ranslocations 162

Other Aberrations 172

Problems 173

Solutions 179

Quantitative Inheritance

Continuous Variation 189

Polygenes 190

189

145

Estimating Number of Gene Pairs Involved in Quantitative Traits 193

Variance 195

Broad Sense Heritability 197

Narrow Sense Heritability 200

Heterosis 201

Thresholds 202

Mapping Quantitative Traits 204

Problems 206

Solutions 212

Reference 218

Population Genetics 219

Concept of Gene Pools 219

Gene and Genotype Frequencies 220

Hardy-Weinberg Principle 224

Hardy-Weinberg Equilibrium 226

Extensions of Hardy-Weinberg Relationships 228

Genetic Drift 231

Migration 232

Mutation 234

Selection 237

A Statistical Approach to Change in a Population 240

Nonrandom Mating 244

Problems 246

Contents

xiii

Contents

8

9

10

xiv

Solutions 251

References 258

Gene Concepts 259

One-Gene One-Enzyme 259

Allelism 263

Bacterial Genetics 268

Bacteriophages 274

Complementation 275

Genetic Fine Structure Analysis in Bacteriophages

Genetic Fine Structure Analysis in Other Organisms

Problems 282

Solutions 291

References 297

Molecular Basis of Heredity 299

Nucleic Acids 299

Nearest Neighbor Frequency Analysis 303

Central Dogma 306

Semiconservative Mode of Replication 307

Replication Forks and Okazaki Fragments 312

Transcription 315

Proteins 31 8

Translation 320

Genetic Code 324

Regulation 330

Operon Systems 332

Mutation 338

Mutation Detection 345

Problems 351

Solutions 359

References 365

Non-Mendelian Inheritance 367

Cytoplasmic Inheritance 367

Male Sterility in Plants 370

Maternal Effects 373

Genomic Imprinting 374

DNA Trinucleotide Repeats 375

Meiotic Drive 376

277 280

1 1

12

B Chromosomes 378

Problems 380

Solutions 383

Human Genetics 389

Mendelian Inheritance in Humans 389

Bias of Ascertainment 392

Epidemiology and Pedigrees 396

Linkage Analysis-Classical Approaches 399

Physical Mapping 400

Human Genome Project 404

Population Genetics 404

Testing Inheritance of a Single Allelic Pair in a Population 405

Consanguinity 409

Methods of Studying the Genetic Basis of Behavior in Humans 415

Twin Studies and Concordance 415

Correlation 419

Heritability 421

Multiple Allelism 423

Disease Associations 425

Problems 427

Solutions 436

References 445

Additional Genetic Analysis Using Statistics 447

More Probability 447

Permutations and Combinations 449

The Binomial Distribution 451

Poisson Distribution 453

Contingency Tables-Test for Independence 456

Problems 459

Solutions 464

Index 473

Contents

xv