Genetics

9 Key excerpts on "Genetics"

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  eBook - ePub

  New Thinking About Genetics

  • Britannica Educational Publishing, Kara Rogers(Authors)
  • 2010(Publication Date)
  • Britannica Educational Publishing

    (Publisher)

  HE STUDY OF GENETICS

  T he study of Genetics forms one of the most rapidly advancing areas of biological research. Since Gregor Mendel’s studies of the transmission of traits in peas, scientists have uncovered the hereditary properties of genes and chromosomes, the chemical structure of DNA, and the mechanisms underlying the translation of the genetic code into proteins. Geneticists today continue to make vital discoveries about the genomes of the organisms that constitute life on Earth. Much of this basic research has led to improved insight into the genetic abnormalities that give rise to disease, as well as to the development of new ways in which the genetic code can be manipulated experimentally to learn more about the functions of individual genes.

  The areas of study encompassed by Genetics cover a broad range of topics—from classical Genetics, the foundation of the field, to comparative genomics, the basis of understanding evolutionary relationships between organisms, to epiGenetics, which has provided startling discoveries about the influence of environmental factors on genes and heredity. The study of Genetics is facilitated by a variety of tools as well, some of which, such as DNA fingerprinting and the polymerase chain reaction, have applications beyond the realm of research.

  CLASSICAL Genetics

  Classical Genetics, which remains the foundation for all other areas in Genetics, is concerned primarily with the method by which genetic traits—classified as dominant (always expressed), recessive (subordinate to a dominant trait), intermediate (partially expressed), or polygenic (due to multiple genes)—are transmitted in plants and animals. These traits may be sex-linked (resulting from the action of a gene on the sex chromosomes) or autosomal (resulting from the action of a gene on a chromosome other than a sex chromosome). Classical Genetics began with Mendel’s study of inheritance in garden peas and continues with studies of inheritance in many different plants and animals. Today a prime reason for performing classical Genetics is for gene discovery—the finding and assembling of a set of genes that affects a biological property of interest.

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  Breeding and Hybridization of Food Fishes

  • Biswas, K P(Authors)
  • 2018(Publication Date)
  • Daya Publishing House

    (Publisher)

  The application of genetic methods has made it possible to solve a number of problems specific to such sciences as biochemistry, physiology and embryology in a new and a more efficient way. By making use of hereditary changes and mutations, one can switch off and on almost all physiological processes, interrupt biosynthesis of metabolites in the cell, interrupt morphogenesis and the like. The use of genetic methods in these sciences enables to obtain nearly any model necessary for investigation of one or another problem. Genetics plays quite a special role in the teaching of evolution. Inheritance variability and selection are the main factors of evolution. The This ebook is exclusively for this university only. Cannot be resold/distributed. role Genetics played in consolidating Darwin’s ideas has already been known. Selection involves the effect of gene action, and it is owing to the evaluation of gene action expressed in characters and properties of the organism that selection of genes occurs, creating a most valuable system, a genotype. That is how natural selection operates to create a definite genotype of the organism. Thus Genetics has unraveled the main factors and mechanisms of interrelationship in evolution-inheritance, variability and selection. Thus, Genetics is connected with all theoretical and applied biological sciences, including medicine and agriculture. Inheritance and variability is inherent in all nature, and this determines the position of Genetics in the whole system of biological sciences. This ebook is exclusively for this university only. Cannot be resold/distributed.

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  The Fundamentals of Brain Development

  Integrating Nature and Nurture

  • Joan Stiles(Author)
  • 2008(Publication Date)
  • Harvard University Press

    (Publisher)

  Each discipline provided a different perspective on the question of in-heritance, and during the late nineteenth and the early twentieth cen-turies, each provided unique contributions to the evolving concept of the gene as the material, physical unit of intergenerational inheri-tance. Evolutionary biology focuses on the origins of species and species change over time. Population Genetics takes a quantitative ap-proach, asking about frequencies and distributions of characteristics and traits within and across generations. The study of hereditary trans-mission focuses on single genes and allelic variation. Developmental biology involves the study of the individual organism as it passes from larva to pupa or from embryo to fetus. The very brief history that follows touches on only a small sample of the ideas and discoveries that have contributed to the modern concept of the gene. Indeed, as will be clear, it is a concept that continues to change and evolve. The gene as it was first defined by Johannsen in 1911 is not the gene that Watson and Crick described in 1953, and the gene that Watson and Crick described is not the gene of modern de-velopmental geneticists. There are many threads to the story of the gene and many themes that could be emphasized. The account that follows will focus on three. The first is the overarching issue of ac-counting for both the constancy and the variability of biological inher-itance. It is the most ancient and the most persistent question and it is at the heart of the attempt to define the concept of a gene. The second theme concerns the level of scientific inquiry, because the perception of what a gene is can be influenced by the question the investigator has chosen to ask. An investigator who wishes to understand the source of a trait’s frequency and distribution in a population poses a different question than an investigator who seeks to account for individual vari-32 The Gene

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  Companion to the History of Modern Science

  • G N Cantor, G.N. Cantor, J.R.R. Christie, M.J.S. Hodge, R.C. Olby(Authors)
  • 2006(Publication Date)
  • Routledge

    (Publisher)

  33 The Emergence of Genetics Robert Olby DOI: 10.4324/9780203191873-39

  A nineteenth-century biologist would have been perplexed if he were asked to explain what a ‘geneticist’ studies. A ‘genetic’ study implied a developmental one, tracing the history of, for example, the growth of intelligence from birth to maturity. Those who studied hereditary transmission were regarded as students of the broad field of ‘inheritance’, which was concerned as much with questions of development and evolution as with transmission. The narrower conception of inheritance, in which attention was focused on hereditary transmission, was referred to as ‘heredity’ in the latter part of the nineteenth century, and it was this conception of the field which was understood by the term ‘Genetics’. Yet, like psychology, which has a long history rooted in the philosophy of mind, Genetics has a long history located in theories of ‘generation’. A problem for the historian is, then, to settle on a strategy for relating the Genetics of the twentieth century with the study of inheritance and of hybridism in previous centuries.

  If we turn to definitions of inheritance in the earlier period we find that they rely on the analogy with the inheritance of estate, thus emphasising the transmission of the possessions of one individual, some of which he may have acquired in his own lifetime. The use of the term ‘inheritance’ was thus metaphorical, and to an extent misleading. As J. Arthur Thomson (1861–1933) pointed out, the use of phrases borrowed from the inheritance of property is ‘apt to cause obscurity and fallacy when applied to the inheritance of characters which literally constitute the organism and are inseparable from it’.1 In the biological literature, inheritance was not really a subject in its own right, rather it was a feature of a fundamental property of living things, namely generation. Discussions of inheritance tended, as a result, to be closely concerned also with theories of fertilisation and development. From the Greeks came the material theory of Hippocrates, several versions of which were offered in the eighteenth century. Charles Darwin resurrected the theory in the nineteenth century and called it ‘Pangenesis’. The ‘seed’ or representatives of the various parts of the body of both male and female was accumulated in the gonads. Such a process allowed for the inheritance of acquired characters since acquired structures, just like congenital structures, could supply their representatives. Many other features of generation could also be explained by the theory, for example, regeneration and development. From Aristotle came the form and matter theory. The female contributed the matter and nourishment of the embryo, the male the form. This theory rested in turn upon his conception of substance, according to which the existence of an organism depended upon the intimate union of matter and form. Such a conception allowed the development of the organism to be envisaged as a progressive transformation starting with the apparently formless matter of the egg. This ‘epigenetic’ theory contrasted with the ‘preformationist’ theory according to which a miniature of the adult was formed which was not transformed but simply enlarged in development, and with the theory of ‘pre-existence’ which claimed that all individuals were present at Creation in miniature form, packed one within the other like Russian dolls.2

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  Emery and Rimoin's Principles and Practice of Medical Genetics and Genomics

  Foundations

  • Reed E. Pyeritz, Bruce R. Korf, Wayne W. Grody(Authors)
  • 2018(Publication Date)
  • Academic Press

    (Publisher)

  1 Medicine in a Genetic and Genomic Context ∗ Reed E. Pyeritz Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States Abstract The idea that all diseases are to greater or lesser degrees “genetic” is far from a new concept. The advent of genomics, which makes possible the study of the Genetics of diseases of complex origin in families of patients who have affected relatives as well as in those who do not, emphasizes that genetic variation underlies the latter no less than the former. In disease, the variant gene products and the experiences of the environment with which they are incongruent account for characteristic signs and symptoms. Understanding the meaning of individuality in medicine will enable improved possibility and plausibility of prevention and treatment. Keywords Genetic etiology; homeostasis; pathoGenetics; precision medicine 1.1. Introduction: Our History The history of science is characterized by an exponential rate of expansion [1]. No aspect has escaped, but biology, which is relatively new, has by all accounts exploded. Naturally, these changes are reflected in new principles, new thinking, and new ways of handling new information. Among the problems created is that of making these novelties available to practitioners of science of all kinds. Among the ways suitable to medicine are massive print volumes that contain detailed summaries of diseases, usually of one class, such as endocrine, gastroenterological, or, as in the case of Principles and Practice of Medical Genetics and Genomics (PPMGG), inherited. And of course, the pace of change requires revisions, always characterized by increases that reflect the rate of accumulation. Fission adds volumes whose pages, chapters, contributors, and diseases all do their best to obey the exponential imperative

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  Biological Influences on Criminal Behavior

  • Gail Anderson(Author)
  • 2019(Publication Date)
  • CRC Press

    (Publisher)

  3

  Genetic principles

  Introduction

  This chapter introduces some basic concepts of Genetics. Without this knowledge, it would be impossible for you to decide whether Genetics can or cannot influence crime, and one must understand Genetics to understand how natural selection acts. This chapter provides a very basic overview of Genetics and the patterns of inheritance. This will allow you to appreciate the complexity of Genetics, meiosis, and patterns of inheritance and explain some of the terms used. By the end of this chapter, you should have an understanding of basic inheritance patterns and realize that although Genetics influences our behavior, our genotype interacts with our environment and that DNA alone is not destiny.

  Introduction to Genetics

  Most people who are not trained in biology tend to ignore Genetics, but they still draw conclusions about biological factors and experiments. Their conclusions are usually wrong because they do not understand the basic concepts of biology. This text will not look at complex genetic issues, only at basic biology; most of you will have covered this in high school. It should, however, provide the background needed to begin to understand Genetics. It will show how the body works in relation to its environment and how natural selection acts. Darwin (1809–1892) did not know about Genetics, although the man who is considered the father of Genetics, Gregor Mendel (1822–1884), an Austrian monk, was alive at the same time as Darwin. It is one of the curiosities of the history of science that neither of them fully understood the importance of each other’s work during their lifetimes; years later, someone else read both their works and figured out the relationship. Sadly, after his death, Darwin was found to have a copy of Mendel’s famous paper with notations in the margins of the first few pages, but he obviously had not read further.

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  Stochastic Processes In Genetics And Evolution: Computer Experiments In The Quantification Of Mutation And Selection

  Computer Experiments in the Quantification of Mutation and Selection

  • Charles J Mode, Candace K Sleeman(Authors)
  • 2012(Publication Date)
  • World Scientific

    (Publisher)

  This overview begins with a review of the concept of a gene and then proceeds to a view of how this concept has changed in light of mi-cro array experiments with samples of DNA . Then, as the concept of a 505 506 Stochastic Processes in Genetics and Evolution gene progresses, selected topics from molecular Genetics are introduced to provide a more firm basis for our thinking about the driving forces of evo-lution, mutation and selection. Finally, three specific examples of genes at the molecular level are given in an attempt to anchor our thinking in some actual observations that have been made by experimenters working in the field of molecular Genetics. To readers of books on mathematical Genetics, in which little attention has in the past be given to molecular Genetics, it should be made clear that the material presented in this chapter was mo-tivated by a desire and an attempt to develop a more complete framework in which to further the development of mathematical Genetics. To special-ist in molecular Genetics, however, the overview attempted in this chapter will, no doubt, be lacking in essential details and for such readers, who may glance at the contents of this chapter, we request their forbearance. 13.2 A Brief History of the Definition of a Gene The history of the definition of a gene began with the publication of Mendel’s experiments in 1865 with peas. An English translation of the original paper, which was written in German, may be found in the ap-pendix of the well-known textbook Sinnott, Dunn and Dobzhansky (1950). Mendel’s seminal work, however, remained unnoticed until about 1900, when De Vries in Holland, Correns in Germany and von Tschermak in Austria found Mendel’s forgotten paper and recognized its importance. An account of this story may be found in chapter 2 of the book by Sinnott et al.

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  Statistical Genomics

  Linkage, Mapping, and QTL Analysis

  • Ben Hui Liu(Author)
  • 2017(Publication Date)
  • CRC Press

    (Publisher)

  More mathematically inclined biologists, such as Fisher, Haldane and Wright, laid out the basic theories for population and quantitative Genetics early this century. Population and quantitative Genetics use mathematical and statistical models to extend Mendelian Genetics to multiple-gene models for the analysis of populations and complex traits. After the work of Fisher, Haldane and Wright, and until the late 1970s, development of population and quantitative Genetics was largely involved with extension and validation of their pioneering theories, or for practical applications, such as plant and animal breeding. A new frontier for population and quantitative Genetics was created with the use of molecular methods of mapping and sequencing that generated the mass of new information for genetic research.

  The nature of the gene, its genetic and physical location in the genome, its DNA sequence and physical structure, its effects in terms of biochemistry and quantitative Genetics have been major issues. Different branches of Genetics have had different ways to approach these issues. A gene is both a segment of a chromosome (cytoGenetics) and a stretch of functional DNA (molecular Genetics). However, genetic effects are defined more precisely in quantitative Genetics than in any other branch of Genetics.

  In this chapter, Genetics basics relevant to genomics will be discussed. These include: 1) meiosis and recombination in cytoGenetics, 2) gene frequency and additive and dominant genetic effects in population and quantitative Genetics and 3) DNA sequence and gene expression in molecular Genetics.

  2.2  MENDELIAN Genetics AND CYTOGenetics

  Although techniques used by genomics are largely generated by molecular, quantitative and population Genetics, genetic concepts and terminology are largely derived from Mendelian Genetics and cytoGenetics. It is essential to review and understand the concepts of Mendelian Genetics and cytoGenetics.

  2.2.1  MENDELIAN Genetics Terminology

  Mendelian Genetics is concerned with classical simple trait segregation theory and simple linkage Genetics. A gene is defined as a unit of heredity. In a population of individuals of a sexually reproducing species, a single gene is passed from generation to generation following simple Mendelian inheritance. Each diploid individual has two copies (alleles) of each gene. It is also common to call an allele ‘a gene’ and a gene ‘a gene pair’. For example, gene A may have two alleles in a population, A and a. If an individual has two copies of A, then the genotype of the individual is AA and it is homozygous. An individual with the Aa genotype is heterozygous and an individual with the aa

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  Visualizing Human Biology

  • Kathleen A. Ireland(Author)
  • 2018(Publication Date)
  • Wiley

    (Publisher)

  Genotype Molecular subtype of protein Efficiency of information processing (Biological) endophenotypes Behavior with complex functional interactions (including drug response) Biotechnology Has Far-Reaching Effects 479 The picture is complicated now, and the only thing we can say for sure is that better knowledge of Genetics will make the issue of prena- tal testing even more complex. A strong basic understanding of human Genetics will help prepare you to answer the difficult questions you may confront during your reproductive years. Concept Check 1. What can be learned from a family pedigree? 2. Which chromosome carries the genes for sex-linked traits? 3. How is Tay-Sachs disease inherited? 4. Why do some couples chose prenatal testing? 21.4 Biotechnology Has Far-Reaching Effects LEARNING OBJECTIVES 1. List four biotechnologies used in modern research. 2. Define genetic modification and transgenic organism. 3. Explain how biotechnology supports the theory of evolution. DNA is DNA. When you work with it in the laboratory, it makes little dif- ference where it came from, as all DNA is composed of the same four nucleotides, held in the same basic arrangement. What makes each organism—and each individual—unique is the sequence of nucleo- tides attached to the sugar-phosphate backbone. To read the “language” of Genetics, we must identify the sequence of bases encoded in DNA. The techniques used to isolate DNA and I Wonder. . . Can We Create Super-Babies? Do you want a child with dark hair? Musical talent? Muscular stamina? As we learn more about the human genome, we come closer to under- standing just how traits like these are inherited. Originally, the human genome was mapped in order to identify those genes related to disease. Once these genes were located, the genomes of at-risk people could be scanned to determine whether these individuals carried the same deleterious gene.

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