150-16thegeneticcode[1]

150-16thegeneticcode[1] - Foundations of Biological Science...

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Foundations of Biological Science I (BioSci 150) C How Genes work - Genes code for proteins; the genetic code
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Foundations of Biological Science I (BioSci 150) C The arginine synthesis pathway: precursor ornithine citrulline arginine enzyme 1 enzyme 2 enzyme 3 After X-raying bread mold, Beadle & Tatum looked for arginine synthesis mutants… 0 Genes code for proteins
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Foundations of Biological Science I (BioSci 150) C How would Beadle & Tatum have screened their collection of irradiated spores for arginine-deficient (arg - ) mutants using minimal and supplemented media?
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Foundations of Biological Science I (BioSci 150) C precursor ornithine citrulline arginine enzyme 1 enzyme 2 enzyme 3 arg1 arg2 arg3 They found 3 mutants that grew only if arginine was present. But one grew if ornithine was substituted for arginine, and another grew if citrulline replaced the arginine… different mutants had different enzyme deficiencies ! 0
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Foundations of Biological Science I (BioSci 150) C Beadle & Tatum coined the expression one gene-one enzyme . Later, when enzymes were shown to be made of one or more polypeptides, this hypothesis became one gene-one polypeptide .
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C The mRNA Hypothesis: Since RNA looks like DNA and is found in both nucleus & cytoplasm, RNA made from DNA is used to make proteins . Since polypeptides are
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150-16thegeneticcode[1] - Foundations of Biological Science...

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