4 Key excerpts on "Genetic Manipulation"

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  eBook - ePub

  The Social Management of Genetic Engineering

  • Peter Wheale, René von Schomberg(Authors)
  • 2019(Publication Date)
  • Routledge

    (Publisher)

  1 The Social Management of Genetic Engineering: An Introduction

  Peter Wheale and Ruth

  Mc Nally

  Many complex technologies pose substantial hazards and risks to individuals, communities, regions, or even to the entire planet. To impose such risks on people without even their tacit consent is undeniably an act of tyranny. (Zimmerman 1995, p. 92.)

  Genetic engineering is the manipulation of heredity or the hereditary material, and its aim is to alter cells and organisms so that they produce more or different chemicals or perform better or new functions. It is a pre-modern activity in the sense that people have tampered with heredity for as long as they have been cultivating crops and breeding livestock, and are responsible for countless alterations of the inherited properties of life forms on the planet. However, in this century, the science of genetics has transformed the traditional craft of genetic engineering into a modern science-related technology (see Freeman and Soete 1997, p. 15). The basic principles of classical genetics, which were developed between 1910 and 1940, changed the study of inheritance from a descriptive, anecdotal account of various hybrid crosses to a rigorous science. Applications of the principles of classical genetics had a profound effect on crop plant and domestic breeding, as 'rule-of-thumb' breeding procedures were replaced with rational regimes of artificial selection and hybridization, and artificial in vivo mutagenesis was used to generate genetic variation (see, for example, Stent 1971; Maener 1979).

  Scientific breakthroughs in microbiology, biochemistry and molecular biology since the Second World War comprise what is now often referred to as the 'molecular revolution' in the science of genetics, and it is 'molecular genetics' which underpins recombinant deoxyribo(se)nucleic acid (rDNA) technology. Scientists are now able to decode, compare, construct, mutate, excise, join, transfer and clone specific sequences of DNA, thus directly manipulating genetic material to produce organisms, cells and subcellular components. It is this microgenetic engineering (Wheale and Mc Nally 1988, chapters 1

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  eBook - ePub

  Principles of Gene Manipulation and Genomics

  • Sandy B. Primrose, Richard Twyman(Authors)
  • 2013(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  CHAPTER 1

  Gene manipulation in the post-genomics era

  Introduction

  Since the beginning of the last century, scientists have been interested in genes. First, they wanted to find out what genes were made of, how they worked, and how they were transmitted from generation to generation with the seemingly mythic ability to control both heredity and variation. Genes were initially thought of in functional terms as hereditary units responsible for the appearance of particular biological characteristics, such as eye or hair color in human beings, but their physical properties were unclear. It was not until the 1940s that genes were shown to be made of DNA, and that a workable physical and functional definition of the gene – a length of DNA encoding a particular protein – was achieved (Box 1.1 ). Next, scientists wanted to find ways to study the structure, behavior, and activity of genes in more detail. This required the simultaneous development of novel techniques for DNA analysis and manipulation. These developments began in the early 1970s with the first experiments involving the creation and manipulation of recombinant DNA. Thus began the recombinant DNA revolution.

  Gene manipulation involves the creation and cloning of recombinant DNA

  The definition of recombinant DNA is any artificially created DNA molecule which brings together DNA sequences that are not usually found together in nature. Gene manipulation refers to any of a variety of sophisticated techniques for the creation of recombinant DNA and, in many cases, its subsequent introduction into living cells. In the developed world there is a precise legal definition of gene manipulation as a result of government legislation to control it. In the UK, for example, gene manipulation is defined as: “… the formation of new combinations of heritable material by the insertion of nucleic acid molecules,produced by whatever means outside the cell, into any virus, bacterial plasmid or other vector system so as to allow their incorporation into a host organism in which they do not naturally occur but in which they are capable of continued propagation.” The propagation of recombinant DNA inside a particular host cell so that many copies of the same sequence are produced is known as cloning.

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  eBook - ePub

  How Food Made History

  • B. W. Higman(Author)
  • 2011(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  CHAPTER TWO Genetics and Geography

  For millions of years, plants and animals evolved through processes of natural selection. As they changed their biological characteristics, and as the earth’s surface and climate experienced dramatic cycles and reshaping, plants and animals changed their geographical locations and dominance through natural migration. By their own means, they found their way from place to place, colonizing and invading, across the globe. The speed with which they could move and their success in achieving dominant status within a niche or region was limited only by their own evolving biological characteristics and by the changing physical conditions in the world around them. Ice and fire, meteor strikes, and massive hurricanes not only created hazards and barriers but also opened opportunities. Different species had different chances. A coconut could float across an ocean and strike root when it washed up on a sandy shore. A crocodile might swim immense distances. Appropriately equipped birds, insects, and seeds might fly or float through the air. But a potato or a breadfruit could not long remain viable in saltwater and a pig needed to feel something solid underfoot.

  The rules of the game changed with domestication. Only then did human beings begin to play a major role in deciding what would grow where. Only after domestication did the world see a self-conscious “artificial selection” and an active redistribution of plants and animals. Rather than depending on whatever food resources a new place, near or far, might have to offer, migrant groups now carried with them food resources they were familiar with, and had already domesticated, in expectation of planting or raising these plants and animals in new environments. For the first time, biogeographical change followed in the wake of human population movements. The choices that were made had dramatic consequences for the global geographical distribution of plants and animals.

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  eBook - ePub

  Human Evolutionary Genetics

  • Mark Jobling, Edward Hollox, Toomas Kivisild, Chris Tyler-Smith(Authors)
  • 2013(Publication Date)
  • Garland Science

    (Publisher)

  17 .

  6.8 ANALYZING GENETIC DATA IN A GEOGRAPHICAL CONTEXT

  Until now our consideration of population subdivision has focused solely on a qualitative measure—the population affiliation of a given individual. This neglects some quantitative knowledge about each data point, namely its geo-graphical location. Individuals 1, 2, and 3 may belong to populations A, B, and C respectively; however, if populations A and B are neighbors, whereas C is further away, some information has been overlooked. By incorporating this information we can start to integrate genetic data with information about the landscape from which they were sampled. For example, high levels of differentiation between two nearby populations may result from the presence of a mountain range separating them. By relating genetic data to specific geographical locations we can also attempt to integrate patterns of modern diversity with past geographical processes, for example, sea level changes that resulted in the formation of land bridges.

  Geographical analyses of genetic data allow us to partially disentangle the relative contributions of history and geography to modern genetic diversity.34 In the absence of external, nongenetic, information, it can be difficult to discern whether geographical constraints or historical episodes account for observed patterns of genetic diversity. In many cases, the first step is to test whether the genetic data show any form of geographic structure. There must be demonstrable geographical patterning before any explanation need be sought. This is analogous to the tests for population subdivision discussed earlier in this chap-ter. Once patterning has been detected, it is necessary to determine the nature of the pattern: Are certain alleles found in patches? Or do smooth gradients of allele frequencies span the sampled area? Such gradients of allele frequencies are known as clines

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