Polygenic traits so if there are 8 loci 38 6561

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Unformatted text preview: n = number of loci with two alleles that influence the characteristic. Polygenic Traits • So, if there are 8 loci, 38 = 6561 different genotypes. • Many different phenotypes with only slight differences. • Add in the environment, and there’s even more variation • We’ll return to quantitative traits later (assuming we have time) Chapter 6: Genetic Model Organisms • Genetic model organisms – Why and how we use them – Examples Genetic model organisms: why? • The vast majority of organisms – Use the same genetic material (DNA or RNA) – Use the same genetic code – Use many of the same genes to accomplish the same tasks. • Indicates that all life on earth evolved from the same primordial ancestor (3.5-4 billion years ago) • Thus, the study of other organisms can provide insight into human biology, and ultimately the treatment of disease. Genetic model organisms • Organisms with characteristics that are particularly useful for genetic analysis: • short generation time • large number of progeny • adaptable to lab environment • housed and propagated relatively inexpensively • genomes sequenced (recently) Genetic model organisms • 7 major genetic model organisms – Escherichia coli - a bacterium in the human gut – Saccharomyces cerevisiae - baker’s/brewer’s yeast – Caenorhabditis elegans - a microscopic nematode (round worm) – Drosophila melanogaster - fruit fly – Danio rerio - zebrafish (newbie - sequencing ongoing) – Mus...
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