DOCSLIB.ORG

The Hardy-Weinberg Equilibrium: Some Helpful Suggestions

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Hardy-Weinberg Equilibrium: Some Helpful Suggestions the Hardy-WeinbergEquilibrium-Some0 Helpful Suggestions MaryT. Ortiz LorettaTaras Anthea M. Stavroulakis TN college General Biology curricula, the topic of Hardy-Weinberg equilibrium. Our experiences in classical genetics is typically followed by consider- teaching Mendelian probabilities and the Hardy- ation of population and evolutionary genetics. Weinberg model confirm that students enrolled in After fundamental genetic principles are studied, GeneralBiology who have not attainedthe established students are introduced to the Hardy-Weinbergequi- level of proficiency in mathematics have difficulty librium as a continuum of Mendelian Genetics in a participating in class discussions on this topic and population context. Population genetics provides a solving homework problems and examination Downloaded from http://online.ucpress.edu/abt/article-pdf/62/1/20/49339/4450821.pdf by guest on 28 September 2021 logical segue to the study of evolution. Populations questions. adhering to the Hardy-Weinbergequilibrium provide Mendel's laws provide the foundation for discus- a reference for studying evolutionary changes sions of evolutionary and population genetics (Dob- (Journet1986). With this as a startingpoint, Darwin's zhansky et al. 1997).The Hardy-Weinbergequilibrium observations can be justified and quantified, as well is a continuationof Mendel's principles, which show as expanded upon, to include additional aspects of that gene frequenciesunder certainconditions remain population and evolutionary genetics. constant from one generation to the next, thereby The Hardy-Weinbergequilibrium is an algebraic maintaining the allelic composition of the gene pool mathematical tool for predicting allele frequencies, of the population. During our presentation of the phenotypes and genotypes in populations (Cum- Hardy-Weinbergequilibrium, we link Punnettsquares mings 1997; Lewis 1997; Mader 1996;Postlethwait & and probabilitycalculations to previous discussions of Hopson 1995).Mertens (1992)proposed strategies for classicalinheritance. We enrich our students' learning introducingthe Hardy-Weinbergequilibrium to make experiences by extending basic principles of inheri- it meaningful and more useful to both students and tance, and providing challenging mathematicalappli- teachers. It has been our experience that students cations. Instructors can assist students through in- have difficulty with Hardy-Weinbergproblem solv- class practiceproblems. This allows subsequent focus ing. Since students often possess a genuine fear of on Hardy-Weinbergtheory and applications rather mathematics, reinforcement of basic mathematical than laboring over arithmetic operations. principles when working through Hardy-Weinberg We present Hardy-Weinbergtheory as a mathemat- problems will provide a less threatening experience, ical model demonstratinghow allelic and genotypic thereby enabling students to successfully complete frequencies remain constant in a large population problems and concentrate on understanding genetic under specified conditions. Named after its discover- concepts as they relate to population dynamics (Flan- ers, Godfrey H. Hardy, a British mathematician,and nery 1995; Journet 1986). Wilhelm Weinberg, a German physician, the Hardy- Various methods, some quite detailed, for present- Weinberg equilibrium requires the following condi- ing the Hardy-Weinbergequilibrium have appeared tions (Campbellet al. 1997; Cummings 1997;Journet in journals and textbooks (Cummings 1997; Journet 1986; Lewis 1997; Mader 1996; Postlethwait & Hop- 1986;Lewis 1997;Mader 1996;Postlethwait & Hopson son 1995): 1995). The Hardy-Weinbergmodel is presented in a 1. No gene flow: Thereis no migrationof individuals variety of ways in General Biology textbooks. In this into or out of the population. paper we offer suggestions for instructors to assist 2. No mutations: Alleles will not change from one with their presentation of this topic. Regardless of generation to the next. the approach, our suggestions can assist instructors 3. No selection:No selective force favors one pheno- by providing a unified method for explaining the type over another. 4. No genetic drift: The population is large; random fluctuations are considered negligible. MaryT. Ortiz, Ph.D., Loretta Taras and AntheaM. Stavroulakis, 5. Random mating: Individuals pair by chance, not Ph.D., are Associate Professors in the Biology Department according to their phenotypes. at Kingsborough Community College, 2001 Oriental Blvd., hold true for a Brooklyn,NY 11235. If the above assumptions given population, and: 20 THEAMERICAN BIOLOGY TEACHER, VOLUME 62, NO. 1, JANUARY2000 p = the frequencyof the dominantallele in a population Information ascertained from the answers to these q = the frequencyof the recessiveallele in a population, questions allows students to learn additional aspects about a given population, such as knowing the per- then: p + q = 1 (Equation 1) centage of carriers of a particular genetic disease. and p2 + 2pq + q2 = 1 (Equation 2) During our classroom presentation of the Hardy- Weinberg model, it is apparent that a number of Equation 1 is called the Gene Pool Equation, and students are unsure of the mathematicalcalculations. Equation2 is called the Genotype Equation.In Equa- This hesitation with mathematicsinterferes with their tion 1 the sum of the frequencies of all of the alleles ability to solve problems and analyze results. We in a population must equal one (indicating 100%). are frequently asked to provide additional practice For example, if p = 0.2, then q must equal 0.8. In problems. GeneralBiology textbooks usually provide Equation 2 the sum of the frequencies of individuals a few example problems. The instructor may find with each genotype must add up to the entire popula- herself/himself searching for additional problems in tion, or one (100%) (Cummings 1997; Lewis 1997; which the numbers work out without requiring use Mader 1993; Postlethwait & Hopson 1995). of a calculator(Lewis 1997;Mader 1993;Postlethwait Consider the following: Pointy ears are dominant & Hopson 1995). over round ears in an alien population. Let E and Wouldn't it be convenient for instructors to have Downloaded from http://online.ucpress.edu/abt/article-pdf/62/1/20/49339/4450821.pdf by guest on 28 September 2021 e representthe dominant and recessive alleles, respec- a table containing p, q, p2, 2pq and q2 values to tively. In a population of 1,000 aliens, 800 have pointy facilitatequick, on-the-spotconstruction of examples? ears (p = 0.8; q = 0.2). The threepossible genotypes If this table were readily available, problems could in a cross between two heterozygotes are EE, Ee and be generated quickly and abundantly. Table 1 lists ee. We can demonstrate this using a Punnett square: = - p, q, p2, 2pq and q2 values for p and q 0.1 0.9 E e in increments of 0.1. More extensive tables could be constructedusing p and q values with more significant E EE Ee digits, such as 0.11, 0.12, 0.13, etc. Use of the p and q values in Table 1 to generate problems allows instructors to focus their lesson on the significance e Ee ee of the Hardy-Weinbergequilibrium instead of arith- metic. For example, in a population meeting the the if Using the values for E and e, p = 0.8 and q = 0.2, requirementsof Hardy-Weinbergequilibrium, respectively, we can use a Punnett square to calculate p = 0.7, find the frequency of: the predicted frequencies for each genotype: a. the recessive allele b. homozygous dominants q c. heterozygotes (carriers) p p2 = 0.64 or 64% d. homozygous recessives = 2 pq pq 0.16 or 16% ppp=p 0.04 or 4% e. dominant phenotypes q2= in the population. Using Table 1, the answers to a through e are 0.3, 0.49, 0.42, 0.09 and 0.91, respec- tively. That is, 3% of the population in question q pq qq=q2 contain the recessive allele, 49% are homozygous dominant, 42% are heterozygous (carriers),9% are Therefore, using Equation 2: homozygous recessive, and 91%display the dominant phenotype. 0.64 + (2 x 0.16) + 0.04 = 1 a states that the frequency of 64% + 32% + 4% = 100% Suppose problem sickle-cell anemia, an autosomal recessive condition Once the components of the equation are deter- is 20% in a given population. We have found that mined, students can be challenged with a variety of a quick review of conversions between percents and questions, as well as formulate their own practice decimals helps guide students through the mechanics problems, including: of the problem. Conversion of 20% to a decimal for 1. What percent of the population would you expect use in Equations 1 and 2 requires dividing by 100 to be homozygous dominant? (Answer: 64%) or moving the decimal point two places to the left 2. What percent of the population would you expect to obtain 0.2. Likewise, changing a decimal to a to be homozygous recessive? (Answer: 4%) percent requires multiplying by 100, or moving the 3. What percent of the population would you expect decimal point two places to the right. to be heterozygous? (Answer: 32%) Another rule of mathematics is often overlooked 4. What percent of the population would you expect by students: When multiplying factors containing to show the dominant phenotype? (Answer: 96%) decimals, the number of decimal places in the product HARDY-WEINBERGEQUILIBRIUM 21 Table 1. p, q, p2 2pq and q2 values for p and q = 0.1-0.9 in increments of 0.1. p 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 q 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 p2 0.01 0.04 0.09 0.16 0.25 0.36 0.49 0.64 0.81 2pq 0.18 0.32 0.42 0.48 0.50 0.48 0.42 0.32 0.18 q2 0.81 0.64 0.49 0.36 0.25 0.16 0.09 0.04 0.01 must equal the sum of the decimal places in each point, we distributed Tables 1 and 2 to our classes. of the factors in the problem. For example, this is Using the tables, students solved Hardy-Weinberg encounteredwhen multiplying 0.1 by 0.1.
Load more

Recommended publications
  • Models of the Gene Must Inform Data-Mining Strategies in Genomics
    entropy Review Models of the Gene Must Inform Data-Mining Strategies in Genomics Łukasz Huminiecki Department of Molecular Biology, Institute of Genetics and Animal Biotechnology, Polish Academy of Sciences, 00-901 Warsaw, Poland; [email protected] Received: 13 July 2020; Accepted: 22 August 2020; Published: 27 August 2020 Abstract: The gene is a fundamental concept of genetics, which emerged with the Mendelian paradigm of heredity at the beginning of the 20th century. However, the concept has since diversified. Somewhat different narratives and models of the gene developed in several sub-disciplines of genetics, that is in classical genetics, population genetics, molecular genetics, genomics, and, recently, also, in systems genetics. Here, I ask how the diversity of the concept impacts data-integration and data-mining strategies for bioinformatics, genomics, statistical genetics, and data science. I also consider theoretical background of the concept of the gene in the ideas of empiricism and experimentalism, as well as reductionist and anti-reductionist narratives on the concept. Finally, a few strategies of analysis from published examples of data-mining projects are discussed. Moreover, the examples are re-interpreted in the light of the theoretical material. I argue that the choice of an optimal level of abstraction for the gene is vital for a successful genome analysis. Keywords: gene concept; scientific method; experimentalism; reductionism; anti-reductionism; data-mining 1. Introduction The gene is one of the most fundamental concepts in genetics (It is as important to biology, as the atom is to physics or the molecule to chemistry.). The concept was born with the Mendelian paradigm of heredity, and fundamentally influenced genetics over 150 years [1].
    [Show full text]
  • Epigenetics Is Normal Science, but Don't Call It Lamarckian
    Extended Abstract Volume 6:3, 2020 DOI: 6.2472/imedipce.2020.6.002 Journal of Clinical Epigenetics ISSN: 2472-1158 Open Access Epigenetics is Normal Science, But Don’t Call It Lamarckian David Penny New Zealand Extended Abstract they are general (but not necessarily universal) because they are found in Excavates, which many people consider are ancestral to other eukaryotes [6, 7]. Similarly, an important point is that Epigenetic mechanisms are increasingly being accepted as an integral methylation, phosphorylation, etc. of the DNA and of the histones is a part of normal science. Earlier genetic studies appear to have part of normal evolution (at least in eukaryotes that have the assumed that the only changes were ‘mutations’ as a result of a nucleosome structure) [8]. One of the most interesting aspects is change in the DNA sequence. If any such changes altered the amino methylation (and hydroxymethylation) of cytosine, and this is found in acid sequences then it was effectively a mutation, and if it occurred in many deep branching eukaryotes [9]. Typically there is methylation of a germline cell (including in unicellular organisms) then it could be cytosine molecules, especially in CpG (cytosine followed by guanine) passed on to subsequent generations. However, it is increasingly regions. The role of small RNAs in helping regulate the levels of apparent that other changes are also important, for example, changes protein expression is discussed in [10]. The main point here is that to methylation patterns, and to the histone proteins. Epigenetics was protein expression levels are very variable in all cells – it is not just sometimes consider ‘additional’ to classical genetics, but it is still fully classical genetics that is important; there are many epigenetic dependent on DNA, RNA and protein sequences, and at least since [1] mechanisms affecting the differences in protein expression.
    [Show full text]
  • Using Classical Genetics Simulator (CGS) to Teach Students the Basics of Genetic Research
    Tested Studies for Laboratory Teaching Proceedings of the Association for Biology Laboratory Education Vol. 33, 85–94, 2012 Using Classical Genetics Simulator (CGS) to Teach Students the Basics of Genetic Research Jean Heitz1, Mark Wolansky2, and Ben Adamczyk3 1University of Wisconsin, Zoology Department, 250 N. Mills Street, Madison WI 53706 USA 2University of Alberta, Department of Biological Science, Edmonton AB, CAN T6G 2E9 3Genedata, MA, A-1 Cranberry HI, Lexington MA 02421 USA ([email protected];[email protected];[email protected]) Some experiments are not well suited to large introductory labs because of space, time and funding constraints. Among these are classical Mendelian genetics investigations. Cyber labs can overcome these constraints. Classi- cal Genetics Simulator (CGS) gives students the opportunity to perform controlled crosses with model organisms much like a geneticist would do. CGS provides populations of Drosophila, Arabidopsis or mice with unknown patterns of inheritance and gives students the tools to design and perform experiments to discover these patterns. Students require an understanding of the what, why and how of solving genetic problems to successfully complete our cyber genetics lab activities. Keywords: Mendelian genetics, simulator, classical genetics simulator (CGS), linkage, monohybrid, dihybrid Introduction In large introductory biology classes some labs are dif- How can students get practice doing what geneticists ficult to do because of space, time and funding constraints. actually do? Among these are classical Mendelian genetics investiga- An obvious way for students to get practice doing what tions. As a result, we have turned to cyber labs. Working geneticists do is to conduct actual crosses.
    [Show full text]
  • The Sustained Impact of Model Organisms—In Genetics and Epigenetics
    | COMMENTARY The Sustained Impact of Model Organisms—in Genetics and Epigenetics Nancy M. Bonini*,†,1 and Shelley L. Berger‡,1 *Department of Cellular and Developmental Biology, Perlman School of Medicine, †Department of Biology, and ‡Department of Genetics, University of Pennsylvania, Philadelphia, Pennsylvania 19104 KEYWORDS classical genetics; epigenetics; behavior; genomics; human disease Now that DNA sequencing can reveal disease-relevant muta- The Rise of Model Organism Genetics and the tions in humans, it is appropriate to consider the history of Embrace of Molecular Genetics genetic research on model organisms, and whether model Model organism genetics has revealed many fundamental organisms will continue to play an important role. Our view is biological processes. This was achieved by applying unbiased that genetic research in model organisms has had an in- genetic screens to reveal genes and their mechanisms of disputably enormous impact on our understanding of com- action in processes such as cell cycle control (Nasmyth plex biological pathways and their epigenetic regulation, and 2001), basic body plan specification and mechanisms of de- on the development of tools and approaches that have been velopment (Lewis 1978; Nusslein-Volhard and Wieschaus crucial for studies of human biology. We submit that model 1980), and cell death pathways (Ellis and Horvitz 1986; organisms will remain indispensable for interpreting complex Avery and Horvitz 1987), all of which were recognized with genomic data, for testing hypotheses regarding function, and Nobel prizes. for further study of complex behaviors, to reveal not only The sequencing of genomes revealed the breadth of the novel genetic players, but also the profound impact of epige- conservation of genes, and of entire pathways.
    [Show full text]
  • G14TBS Part II: Population Genetics
    G14TBS Part II: Population Genetics Dr Richard Wilkinson Room C26, Mathematical Sciences Building Please email corrections and suggestions to [email protected] Spring 2015 2 Preliminaries These notes form part of the lecture notes for the mod- ule G14TBS. This section is on Population Genetics, and contains 14 lectures worth of material. During this section will be doing some problem-based learning, where the em- phasis is on you to work with your classmates to generate your own notes. I will be on hand at all times to answer questions and guide the discussions. Reading List: There are several good introductory books on population genetics, although I found their level of math- ematical sophistication either too low or too high for the purposes of this module. The following are the sources I used to put together these lecture notes: • Gillespie, J. H., Population genetics: a concise guide. John Hopkins University Press, Baltimore and Lon- don, 2004. • Hartl, D. L., A primer of population genetics, 2nd edition. Sinauer Associates, Inc., Publishers, 1988. • Ewens, W. J., Mathematical population genetics: (I) Theoretical Introduction. Springer, 2000. • Holsinger, K. E., Lecture notes in population genet- ics. University of Connecticut, 2001-2010. Available online at http://darwin.eeb.uconn.edu/eeb348/lecturenotes/notes.html. • Tavar´eS., Ancestral inference in population genetics. In: Lectures on Probability Theory and Statistics. Ecole d'Et´esde Probabilit´ede Saint-Flour XXXI { 2001. (Ed. Picard J.) Lecture Notes in Mathematics, Springer Verlag, 1837, 1-188, 2004. Available online at http://www.cmb.usc.edu/people/stavare/STpapers-pdf/T04.pdf Gillespie, Hartl and Holsinger are written for non-mathematicians and are easiest to follow.
    [Show full text]
  • Mendelian Gene ” and the ” Molecular Gene ” : Two Relevant Concepts of Genetic Units V Orgogozo, Alexandre E
    The ” Mendelian Gene ” and the ” Molecular Gene ” : Two Relevant Concepts of Genetic Units V Orgogozo, Alexandre E. Peluffo, Baptiste Morizot To cite this version: V Orgogozo, Alexandre E. Peluffo, Baptiste Morizot. The ” Mendelian Gene ” and the ”Molec- ular Gene ” : Two Relevant Concepts of Genetic Units. Virginie Orgogozo. Genes and Evolu- tion, 119, Elsevier, pp.1-26, 2016, Current Topics in Developmental Biology, 978-0-12-417194-7. 10.1016/bs.ctdb.2016.03.002. hal-01354346 HAL Id: hal-01354346 https://hal.archives-ouvertes.fr/hal-01354346 Submitted on 19 Aug 2016 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. ARTICLE IN PRESS The “Mendelian Gene” and the “Molecular Gene”: Two Relevant Concepts of Genetic Units V. Orgogozo*,1, A.E. Peluffo*, B. Morizot† *Institut Jacques Monod, UMR 7592, CNRS-Universite´ Paris Diderot, Sorbonne Paris Cite´, Paris, France †Universite´ Aix-Marseille, CNRS UMR 7304, Aix-en-Provence, France 1Corresponding author: e-mail address: [email protected] Contents 1. Introduction 2 2. The “Mendelian Gene” and the “Molecular Gene” 5 3. Current Literature Often Confuses the “Mendelian Gene” and the “Molecular Gene” Concepts 7 4.
    [Show full text]
  • Molecular Population Genetics
    | FLYBOOK ECOLOGY AND EVOLUTION Molecular Population Genetics Sònia Casillas*,† and Antonio Barbadilla*,†,1 *Institut de Biotecnologia i de Biomedicina, and yDepartament de Genètica i de Microbiologia, Campus Universitat Autònoma de Barcelona (UAB), 08193 Cerdanyola del Vallès, Barcelona, Spain ORCID IDs: 0000-0001-8191-0062 (S.C.); 0000-0002-0374-1475 (A.B.) ABSTRACT Molecular population genetics aims to explain genetic variation and molecular evolution from population genetics principles. The field was born 50 years ago with the first measures of genetic variation in allozyme loci, continued with the nucleotide sequencing era, and is currently in the era of population genomics. During this period, molecular population genetics has been revolutionized by progress in data acquisition and theoretical developments. The conceptual elegance of the neutral theory of molecular evolution or the footprint carved by natural selection on the patterns of genetic variation are two examples of the vast number of inspiring findings of population genetics research. Since the inception of the field, Drosophila has been the prominent model species: molecular variation in populations was first described in Drosophila and most of the population genetics hypotheses were tested in Drosophila species. In this review, we describe the main concepts, methods, and landmarks of molecular population genetics, using the Drosophila model as a reference. We describe the different genetic data sets made available by advances in molecular technologies, and the theoretical developments fostered by these data. Finally, we review the results and new insights provided by the population genomics approach, and conclude by enumerating challenges and new lines of inquiry posed by in- creasingly large population scale sequence data.
    [Show full text]
  • A Century of Geneticists Mutation to Medicine a Century of Geneticists Mutation to Medicine
    A Century of Geneticists Mutation to Medicine http://taylorandfrancis.com A Century of Geneticists Mutation to Medicine Krishna Dronamraju CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2019 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Printed on acid-free paper International Standard Book Number-13: 978-1-4987-4866-7 (Paperback) International Standard Book Number-13: 978-1-138-35313-8 (Hardback) This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint. Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, trans- mitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, please access www.copyright .com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc.
    [Show full text]
  • 00326673.Pdf
    Unda_standing Inheritance ~ hat like begets like–that what is now called a species begets offspring ;! of the same species—must have been evident to the earliest humans. ;! Recognition of the inheritance of variations within a species must also j; have come early, since domestication of animals undoubtedly involved II !-i elimination of individuals with undesirable characteristics (a penchant for human flesh, for example). The first animals to be domesticated may well have been members of the dog family, which were used as food, and domestication of canines may have started even before the advent of Homo” sapiens. The remains of an old hominid relative of ours, Hmno erectus (also known as Java or Peking man), have been found associated with those of a dog-like animal in 500,000-year-old fossils. The earliest canine remains associated with our own species are a mere 12,000 years old. The domestication of food plants probably began between 8000 and 9000 years ago, although some authorities contend that the domestication of cereals preceded that of most animals. Humans must also have very early related treating between “male” and “female” animals, including humans, with the subsequent issuance of offspring. Sexual repro- duction in plants was probably recognized much later—many plants, after all, are discreet] y bisexual—but at least 4000 years ago, as evidenced by the Babylonians’ selective breeding, through controlled pollination, of the date palm (Ph~jeni.~ du(fylif- eru),which occurs as separate male and female trees. (The dates borne by a female tree result from fertilization of its eggs by spern-containing pollen from male trees.) The oldest recorded thoughts about heredity appear in the religious writings of the ancient Hindus and Jews, which reveal recognition of the heritability of disease, health, and mental and physical characteristics.
    [Show full text]
  • Population Genetics
    AccessScience from McGraw-Hill Education Page 1 of 15 www.accessscience.com Population genetics Contributed by: C. C. Li Publication year: 2014 The study of both experimental and theoretical consequences of mendelian heredity on the population level, in contradistinction to classical genetics which deals with the offspring of specified parents on the familial level. The genetics of populations studies the frequencies of genes, genotypes, and phenotypes, and the mating systems. It also studies the forces that may alter the genetic composition of a population in time, such as recurrent mutation, migration, and intermixture between groups, selection resulting from genotypic differential fertility, and the random changes incurred by the sampling process in reproduction from generation to generation. This type of study contributes to an understanding of the elementary step in biological evolution. The principles of population genetics may be applied to plants and to other animals as well as humans. See also: MENDELISM . Mendelian populations A mendelian population is a group of individuals who interbreed among themselves according to a certain system of mating and form more or less a breeding community. These individuals share a common gene pool which is the total genic content of the group. A mendelian population is the unit of study in population genetics. The population may be very large or very small, and is to be distinguished from species or varieties, which may consist of numerous isolated or partially isolated mendelian populations. Mendelian population is a genetic rather than a taxonomic term. Mendelian populations differ from each other in their genic content or chromosomal organization, not necessarily in their taxonomic features.
    [Show full text]
  • Chapter 2. the Beginnings of Genomic Biology – Classical Genetics Contents
    Chapter 2. The beginnings of Genomic Biology – Classical Genetics Contents 2. The beginnings of Genomic Biology – classical genetics 2.1. Mendel & Darwin – traits are conditioned by genes CHAPTER 2. THE BEGINNINGS OF GENOMIC 2.2. Genes are carried on chromosomes 2.3. The chromosomal theory of inheritance BIOLOGY –CLASSICAL GENETICS 2.4. Additional Complexity of Mendelian Inheritance 2.4.1. Multiple alleles 2.4.2. Incomplete dominance and co-dominance 2.4.3. Sex linked inheritance 2.4.4. Epistasis It should be clear that the beginings of genomic 2.4.5. Epigenetics 2.5. Genes on the Same Chromosome are Linked biology are grounded in classical or Mendelian Genetics. 2.5.1. Meiosis: chromosomes assort independently Once the relationship between traits and genes was 2.5.2. Mapping genes on chromosomes understood, the relationship between cells and genetics 2.6. Quantitative Genetics: Traits that are Continuously Variable was investigated, leading to the discovery of 2.7. Population Genetics: Traits in groups of individuals chromosomes, and a quest for the substance that carried the genetic information began, culminating in the discovery of DNA. These studies constitute the contribution of classical genetics to the founding of the genomic era. CONCEPTS OF GENOMIC BIOLOGY Page 1 In 1859 Charles Darwin published his book On the (RETURN) Origin of Species. In this work Darwin described a mass of descriptive support for the concept that 2.1. MENDEL & DARWIN – “traits” are stably transmitted through subsequent TRAITS ARE CONDITIONDBY GENES. generations, and that organisms that have superior traits survive their natural environment to pass those The idea of genomic biology begins with a traits on to the next generation.
    [Show full text]
  • Max Planck Institute for the History of Science Making Mutations
    MAX-PLANCK-INSTITUT FÜR WISSENSCHAFTSGESCHICHTE Max Planck Institute for the History of Science 2010 PREPRINT 393 Luis Campos and Alexander von Schwerin (eds.) Making Mutations: Objects, Practices, Contexts Table of Contents The Making of “Making Mutations”.........................................................................................3 Alexander von Schwerin & Luis Campos Identifying Mutation Women in Mutation Studies: The Role of Gender in the Methods, Practices, and Results of Early Twentieth-Century Genetics ......................................................................................11 Marsha L. Richmond Mutant Sexuality: The Private Life of a Plant.........................................................................49 Luis Campos Generating Plants and Women: Intersecting Conceptions of Biological and Social Mutations in Susan Glaspell's “The Verge” (1921)................................................................71 Jörg Thomas Richter Non-Evolutionary Mutants? A Note on the Castorrex Rabbit ................................................85 Thierry Hoquet Organisms Tracing the Totsuzen in Tanaka's Silkworms: An Exploration of the Establishment of Bombyx Mori Mutant Stocks................................................................................................ 109 Lisa A. Onaga Supporting the Balance View: Dobzhansky’s Construction of Drosophila pseudoobscura ...................................................................................................................... 119 Matt Dunn The First
    [Show full text]