Heredity

9 Key excerpts on "Heredity"

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  Britannica Guide to Genetics

  • Encyclopaedia Britannica, Inc.(Authors)
  • 2009(Publication Date)
  • Encyclopaedia Britannica, Inc.

    (Publisher)

  Genetics may be defined as the study of genes at all levels, including the ways in which they act in the cell and the ways in which they are transmitted from parents to offspring. Modern genetics focuses on the chemical substance that genes are made of, DNA, and the ways in which it affects the chemical reactions that constitute the living processes within the cell. Gene action depends on interaction with the environment. Green plants, for example, have genes containing the informa-tion necessary to synthesize the photosynthetic pigment chlor-ophyll that gives them their green colour. Chlorophyll is synthesized in an environment containing light because the gene for chlorophyll is expressed only when it interacts with light. If a plant is placed in a dark environment, chlorophyll synthesis stops because the gene is no longer expressed. Genetics as a scientific discipline stemmed from the work of Gregor Mendel in the middle of the 19th century. Mendel suspected that traits were inherited as discrete units, and, although he knew nothing of the physical or chemical nature of genes at the time, his units became the basis for the development of the modern understanding of Heredity. All present research in genetics can be traced back to Mendel's discovery of the laws governing the inheritance of traits. The word gene , coined in 1909 by Danish botanist Wilhelm Johannsen, has given genetics its name. Ancient Theories of Pangenesis and Blood in Heredity Although scientific evidence for patterns of genetic inheritance did not appear until Mendel's work, history shows that humankind must have been interested in Heredity long before HISTORICAL BACKGROUND 55 the dawn of civilization. Curiosity must first have been based on human family resemblances, such as similarity in body structure, voice, gait, and gestures. Such notions were instru-mental in the establishment of family and royal dynasties.

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  The Human Body

  An Introduction to Structure and Function

  • Adolf Faller, Michael Schuenke(Authors)
  • 2011(Publication Date)
  • Thieme

    (Publisher)

  39 2 Genetics and Evolution Contents Genetics (The Science of Heredity) 40 Genes, Chromosomes, and the Genome 40 The Allele 40 Dominance, Recessiveness, and Codominance 41 Phenotype and Genotype 41 The Mendelian Rules 41 − The Rule of Uniformity (Dominance) 42 − Rule of Segregation 44 − Rule of Independence 45 Autosomal Dominant Hereditary Transmission 46 Autosomal Recessive Hereditary Transmission 48 Sex-linked Inheritance 50 − X Chromosome-linked Dominant Inheritance 50 − X Chromosome-linked Recessive Inheritance 50 Mutations 51 − Gene Mutations 53 − Chromosome Mutations 53 − Genome Mutations 53 Evolution (The Science of Development; Phylogeny) 55 The Concept of Evolution 55 Factors in Evolution 55 − Selection 55 − Mutation 57 − Recombination 58 − Gene Drift 58 − Isolation 58 Evidence for Evolution 59 − Embryological factors 59 − Homologous Organs 60 − Rudimentary organs 60 − Atavism 61 Summary 61 40 Genetics (The Science of Heredity) Genes, Chromosomes, and the Genome Genetics is the science of Heredity; it deals with the structure and func-tion of the genes. The cells of all living things contain a program that guides their functioning. This program is genetically determined, i.e., it is transmitted to both newly formed cells during every cell division. The transmission must be precise, since otherwise it leads to disturbances in function (mutations, see below). The genetic program consists of in-dividual information units, the genes (= hereditary characters), with each gene determining a specific function. The sum total of all genes is the genome (the human inheritance includes withi n a single se t of chromo-somes approximately 30000−40000 genes; see Chapter 1: The Cell Nu-cleus), which is contained in the sum of chromosomes in each cell nu-cleus. Genes are arranged along the chromosomes in a linear fashion and have a definite location and structure.

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  Advanced Molecular Biology

  A Concise Reference

  • Richard Twyman(Author)
  • 2018(Publication Date)
  • Garland Science

    (Publisher)

  Box 1.1 ). Mendel’s principles of inheritance can be summarized as follows.

  (1) The Heredity and variation of characters are controlled by factors, now called genes, which occur in pairs. Mendel called these factors Formbildungelementen (form-building elements).

  (2) Contrasting traits are specified by different forms of each gene (different alleles).

  (3) When two dissimilar alleles are present in the same individual (i.e. in a heterozygote), one trait displays dominance over the other: the phenotype associated with one allele (the dominant allele) is expressed at the expense of that of the other (the recessive allele).

  Table 1.1: Definitions of some common terms used in transmission genetics

  Term	Definition
  Allele	Broadly, a variant form of a gene specifying a particular trait. At the molecular level, a sequence variant of a gene (q.v. wild-type allele, mutant allele, polymorphism)
  Character	A biological property of an organism which can be detected or measured
  Character mode	A general type of character, e.g. eye color
  Character trait, trait, variant	A specific type of character, e.g. blue eye color
  Gene	Broadly, a hereditary factor controlling or contributing to the control of a particular character. At the molecular level, a segment of DNA (or RNA in some viruses) which is expressed, i.e. used to synthesize one or more products with particular functions in the cell (q.v. gene, cistron, gene expression)
  (Gene) locus	The position of a gene (or other marker or landmark) on a chromosome or physical or genetic map. A useful term because it allows discussion of genes irrespective of genotype or zygosity
  Genetic	Pertaining to genes. Of characters, Heredity and variation arising from the nucleotide sequence of the gene (cf. epigenetic, environmental

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  Breeding and Hybridization of Food Fishes

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

    (Publisher)

  Chapter 7: Genetics in Reproductive Biology Inheritance and Variability Genetics is the science of inheritance and variability. Inheritance is the capacity of the offspring to acquire the characters and peculiarities of development of the parents. Variability is contrary to inheritance, being the ability to change hereditary factors, as well as the manifestation of their properties in the process of development. The most remarkable feature of the reproductive process is that the young shows significant similarity to their progenitors, all species of plants and animals producing offspring resembling themselves. Individual features are inherited by each generation with great precision. Members of the same family will always differ from each other and most or even all of them will differ from their parents,no matter how great resemblance exists between them. In some cases the variability related to distribution of different characters among offsprings operates according to definite laws of inheritance, while in other cases it is related to environmental conditions. Variability due to new gene combination is called combined hereditary variability. In the process of development and vital activity of the organism influenced by both external and internal conditions, hereditary changes appear due to changes of genetic structure and this is mutational variability. When variability is due to a modified manifestation of a character, due to environmental conditions, it is called modification. Here it is not the definite manifestation of the character having a modified variability that is inherited, but the whole range of variation of the character depending on the environment- the so-called reaction norm of the organism. Strictly speaking, there are no hereditary changes, but all the character This ebook is exclusively for this university only. Cannot be resold/distributed.

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  Psychological Criminology

  An Integrative Approach

  • Richard Wortley(Author)
  • 2023(Publication Date)
  • Routledge

    (Publisher)

  3     Heredity

  DOI: 10.4324/9780429299667-3

  The previous chapter on human nature introduced the role played by genes in criminal behaviour and this chapter on Heredity continues that examination. However, where human nature is the product of the intergenerational transmission of genes over the course of human evolutionary history, this chapter is more narrowly concerned with the transmission of genes within the family over just one or two generations. Moreover, the study of human nature is largely concerned with the similarities in genetic make-up across the human species, while the focus here is on genetic variability and individual differences within a given population. Nevertheless, the two approaches are quite consistent with one another. The proposal that humans have a universal, genetically based, psychological structure does not preclude variations in the strength with which certain characteristics are possessed by individuals, and indeed, evolution depends upon genetic variability within a species.

  The aim of this chapter is to examine the extent to which criminality can be attributed to genetic predispositions that are passed down in the family. The field of study that examines the relationship between genetic inheritance and the psychological expression of those genes – in the form of emotions, actions, mood, and personality – is called behavioural genetics. The chapter begins with a brief overview of behavioural genetics before going on to examine the evidence for the heritability of criminality. The chapter concludes with an examination of developments in molecular genetics, a line of research that includes efforts to identify specific genes implicated in the expression of characteristics that increase the probability of criminality.

  A primer in behavioural genetics

  Behavioural genetics is a specialised and complex field bridging biology and psychology, and it is not possible to cover it in detail here. However, it is important that some of the fundamental principles of Heredity be understood to assess the role of genes in criminality.

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  The Human Genome

  A User's Guide

  • Julia E. Richards, R. Scott Hawley(Authors)
  • 2004(Publication Date)
  • Academic Press

    (Publisher)

  Section 1 THE BASICS OF Heredity This section provides a description of how traits are inherited and introduces the concept of the gene. We talk about how some of the basic genetic con-cepts apply to human inheritance and about how patterns of inheritance can look very different depending on the trait you are studying. SLAYING MOLECULAR DRAGONS: BRENDA’S TALE “To dream . . . The impossible dream . . .” —Don Quixote in Man of La Mancha 1 Healthy young people aren’t supposed to die. Even amidst the many dangers that arise from the exuberance and hazards of youth, the death of someone young is always a shock. And when the blow is delivered from some direction we never expected, were not waiting for, had never considered, when someone young is felled by an illness such as leukemia, we are left feeling stunned. It seems impossible to understand such an outcome, and we find ourselves asking, “How could this have happened?” And the next question that comes to mind is, “What can be done so that this does not happen again?” Brenda Knowles was a graduate student in Scott’s lab back in the late 1980s (Figure 1.1). She was bright and funny and totally unimpressed by Scott’s sup-posed seniority. She was trained as a chemist and had begun graduate school doing biochemistry. However, Brenda had a strong connection to biology and the organisms that embody so much more complexity than simple biochem-istry. Soon she found her way into a lab where there were organisms to work on, maybe just fruit flies, but organisms nonetheless. She shared her time in Scott’s lab with the usual array of characters that populate a “working lab”. Science is a business that cherishes eccentricity, even 3 FIGURE 1.1 Brenda Brodeur Knowles (1962–1996). (Photo courtesy of James Knowles.) encourages it. A healthy, growing lab will have its share of unusual characters. The basic foundation on which any new lab is started is unusual and novel ideas.

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  The Mendelian Revolution

  The Emergence of Hereditarian Concepts in Modern Science and Society

  • Peter J. Bowler(Author)
  • 2000(Publication Date)
  • The Athlone Press

    (Publisher)

  The offspring sometimes differs from its parents because it has developed a character transmitted from a more distant ancestor, implying that characters can lie hidden for a number of generations without manifesting themselves. Variation occurs within the population because Heredity transmits a variety of different characters, allowing them to be combined and recombined through sexual reproduction, sometimes with unexpected results. We can now see that variation within a population is maintained because of Heredity: there is no need to postulate a force interfering with Heredity, providing we think of variation as a function of the population, not of individual acts of generation. This transition to seeing variation as a feature of the whole population can be thought of as something lying implicit within the Darwinian selection theory, but obscured by Darwin's continued reliance on a Evolution and Heredity 69 generational model of sexual reproduction as the source of variation. Gallon certainly believed that the ancestral contributions were preserved in the form of material particles transmitted through the cells of the reproductive system. The units composing an individual's inherited stirp will multiply in the germ cells and compete among themselves to see which will contribute to the next generation. Unlike the later Mendelians, Gallon thought that the material particles representing a particular character were capable of indefinite division, so that ever-smaller quantities could be transmitted over many generations. This assumption raised no problems because Gallon deliberately turned his back on the physiological question of how the transmission takes place. Nor did he concern himself with how ihe germinal malerial controls the development of characters in the growing embryo.

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  Inheritance Systems and the Extended Evolutionary Synthesis

  • Eva Jablonka, Marion J. Lamb(Authors)
  • 2020(Publication Date)
  • Cambridge University Press

    (Publisher)

  19 The Extended Evolutionary Synthesis We called the processes, factors and mechanisms that underlie cellular inheri- tance ‘epigenetic inheritance systems’, defining an epigenetic inheritance sys- tem as ‘a system that enables the phenotypic expression of the information in a cell or individual to be transmitted to the next generation’ (Jablonka and Lamb, 1989, p. 292). In 1995 we reviewed the then existing cases of epigenetic inheritance and discussed the evolutionary implications of this type of Heredity in Epigenetic Inheritance and Evolution: The Lamarckian Dimension. Our challenge to the MS was explicit, since our position was that soft inheritance is important in evolution. Epigenetics was not the only field that was challenging ideas about inheri- tance and evolution at the close of the twentieth century. In the 1980s, theore- tical studies of cultural inheritance and cultural changes in populations began to have an impact on thinking about human evolution, and in the 1990s the study of social learning in non-human animals began to take off. Consequently, in 2005 we put the ideas from these blossoming fields together in our book Evolution in Four Dimensions, in which we argued that heritable genetic, epigenetic, beha- vioural and symbolic variations are all important in evolution. Evolution, we suggested, should be defined as a change in the nature and frequency of heritable types (genotypes, epigenotypes and cultural types) over time. 2 Characterizing Inheritance Systems In this Section, we outline the features of the different systems underlying the inheritance of phenotypic variations and give some experimental evidence for their existence. More details are given in Jablonka and Lamb (2014) and Lamm (2018). As a result of new data and fresh thinking, the classification we use here is slightly modified from that used in earlier publications.

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  Child Psychology

  Development in a Changing Society

  • Robin Harwood, Scott A. Miller, Ross Vasta(Authors)
  • 2012(Publication Date)
  • Wiley

    (Publisher)

  MECHANISMS OF INHERITANCE Learning Objective 3.1 IDENTIFY AND DESCRIBE THE MECHANISMS AND PROCESSES BY WHICH PHYSICAL AND BEHAVIORAL CHARACTERISTICS ARE INHERITED. Cell Division Inside the Chromosome Mendel’s Studies • Principles of Genetic Transmission • Principles of Inheritance Since Mendel GENES AND BEHAVIOR Learning Objective 3.2 DESCRIBE THE INFLUENCE THAT GENES HAVE ON THE DEVELOPMENT OF PSYCHOLOGICAL ABILITIES AND TRAITS. Family Studies Adoption Studies Twin Studies INTERACTION OF GENES AND ENVIRONMENT Learning Objective 3.3 HOW DO GENES AND ENVIRONMENT INTERACT TO INFLUENCE THE DEVELOPMENT OF BEHAVIOR? Reaction Range Gene–Environment Correlations Nonshared Environment GENETIC DISORDERS Learning Objective 3.4 DESCRIBE DIFFERENT TYPES OF GENETIC DISORDERS AND THEIR IMPACT ON CHILD DEVELOPMENT. Hereditary Autosomal Disorders • Dominant Traits • Recessive Traits RESEARCH & SOCIETY The Human Genome Project X-Linked Disorders Structural Defects in the Chromosome • Autosomal Defects • Disorders of the Sex Chromosomes Genetic Counseling • A Counseling Session POPULATION SCREENING PATHWAYS TO PARENTHOOD Learning Objective 3.5 DESCRIBE ALTERNATIVE PATHS TO PARENTHOOD Assisted Reproduction • Effects of ART on Child Development Adoption APPLICATIONS Journey to Parenthood CONVERSATIONS with an Adoption Social Worker 3 C H A P T E R 67 Learning Objective 3.1 Identify and describe the mecha- nisms and processes by which physical and behavioral characteris- tics are inherited. Chapter 3 ■ The Biological Context of Development 68 Chromosomes Chemical strands in the cell nu- cleus that contain the genes. The nucleus of each human cell has 46 chromosomes, with the exception of the gametes, which have 23.

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