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Design Media Arts at UCLA
Peter Ng (M)
South Pasadena, US
Immortal since Mar 29, 2007
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    From petergng
    Final Visuals + Sounds
    petergng’s project
    Design Media Arts at UCLA
    In the 1970s space colonies were considered to be a viable alternative to a life restricted to planet Earth. The design of cylindrical space...
    Now playing SpaceCollective
    Where forward thinking terrestrials share ideas and information about the state of the species, their planet and the universe, living the lives of science fiction. Introduction
    Featuring Powers of Ten by Charles and Ray Eames, based on an idea by Kees Boeke.
    From petergng's personal cargo

    Variation and Mutation
    Project: Design Media Arts at UCLA

    Variation

    Evolution consists of two basic types of processes: those that introduce new genetic variation into a population, and those that affect the frequencies of existing alleles.[15] Mutations in genetic material, migration between populations (gene flow), and the reshuffling of genes during sexual reproduction (genetic recombination) create variation in organisms. In some organisms, like bacteria and plants, variation is also produced by the mixing of genetic material between different species in horizontal gene transfer and hybridization. Genetic drift and natural selection act on this variation by increasing or decreasing the frequency of traits: genetic drift does so randomly, while natural selection does so based on whether a trait increases fitness (reproductive success).

    The heritable portion of an individual's apparent traits, or phenotype, is primarily the result of the specific genetic makeup, or genotype, encoded on DNA/protein constructs called chromosomes. Thus, the variation in heritable traits within a population reflects the variation in genetic makeup. A specific location on a chromosome is known as a locus; a variant of a DNA sequence at a given locus is an allele. The modern evolutionary synthesis defines evolution as the change over time in the relative frequencies of alleles in a population.

    Genetic variation is often the result of a new mutation in a single individual (usually point mutations, insertions, or deletions); in subsequent generations, the frequency of that variant may fluctuate in the population, becoming more or less prevalent relative to other alleles at the site. All evolutionary forces act by driving this change in allele frequency in one direction or another. Variation disappears when an allele reaches the point of fixation — when it either reaches a frequency of zero and disappears from the population, or reaches a frequency of one and replaces the ancestral allele entirely. Most sites in the complete DNA sequence, or genome, of a species are identical in all individuals in the population. Consequently, relatively small genotypic changes can lead to dramatic phenotypic ones. Sites with more than one allele are called polymorphic, or segregating, sites. Polymorphism leads to distinct groups of traits arising within the same species, such as different hair colors or sexes. Interactions between a genotype and the environment may also affect the phenotype, as reflected in developmental and phenotypic plasticity.

    Mon, Apr 16, 2007  Permanent link

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