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Development2Lect - Development Nature-Nurture Problem Is a...

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Development “Nature-Nurture Problem” Is a trait due to heredity or to the environment? Sometimes, the problem is stated as maturation vs. enculturation. Environment can be: chemical (enviro toxins; lifestyle exposure, eg, smoking) pathogen psychological (war, famine) pre-, peri-, or post-natal “Nature-Nurture Problem” Error is to state the problem as either-or: Environments can release effects of genes. Genes can control susceptibility to environment. (e.g., Baldwin Effect) Effects of genes vs. environment can rarely be disentangled. “Nature-Nurture Problem” Whether a trait is genetically influenced does not imply that is it fixed (non-plastic): in deprivation dwarfism, malnutrition can override height, which is usually fixed. in phenylketonuria (PKU), a simple dietary change can bypass a genetic flaw. in carotenism people can turn orange by eating too many carrots, or with too much sun they can turn redder and darker. Trait plasticity: how much can the environment affect a trait? -plasticity: how moveable it is Waddington’s “Epigenetic Landscape” -cannalization, Height is deeply cannalized (won’t move around) Epigenetics (“Above” or “Governing” Genetics) Refers to potentially heritable information not contained in the DNA sequences of the genome. “Epigenetic markers” refer to modifications of DNA sequences, and can include: -can switch genes on and off [in twins; 50% if one has schizo] Attachment of methyl (CH 3 ) groups to cytosine-guanine pairs, or acetyl (CH 3 CO) groups to histone proteins that bundle DNA into chromatin bundles. Jumping or transposition of DNA sequences within a stretch of DNA.
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Epigenetic modifications, or “markers,” can switch genes on and off. Although most people have identical genomes in each of their ~250 body cell types, epigenetic markers can differ in each type. Consequences of Epigenetics Because of differences in epigenetic markers, two organisms with identical genomes (e.g., clones) can have different phenotypes (e.g., Dolly, the cloned sheep, aged faster and had arthritis, unlike the original animal)
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