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Pathways

Pathways. Gene A Gene B Enzyme A Enzyme B Substrate -------  intermediate ------ product. Most often the final product of the biochemical pathway is something essential to life, like amino acids , nucleotides , etc. Pathways. One-gene-one-enzyme hypothesis

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Pathways

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  1. Pathways Gene A Gene B Enzyme A Enzyme B Substrate ------- intermediate ------ product Most often the final product of the biochemical pathway is something essential to life, like amino acids, nucleotides, etc.

  2. Pathways • One-gene-one-enzyme hypothesis • George Beadle and Edward Tatum • Neurospora

  3. Pathways • Wild typeNeurospora (all genes intact), will grow on minimal media of mineral salts, glucose and biotin • Has all the genes to make all the proteins to make everything the beasty needs to live and survive

  4. Pathways • Auxotrophs (mutation in one or more genes), will not grow on minimal media of mineral salts, glucose and biotin • Will grow on minimal media only if supplemented with one or more specific nutrients that it cannot make

  5. Arginine auxotroph

  6. Pathways Gene A Gene B Enzyme A Enzyme B Substrate ------- intermediate ------ product Most often the final product of the biochemical pathway is something essential to life, like amino acids, nucleotides, etc.

  7. Pathways Gene A Mutant Gene B Enzyme A No Enzyme B Substrate ------- intermediate No Product Can use mutants to work out pathways, and identify which gene catalyzes which step

  8.   substrate + = growth - = no growth No. 1 No. 2 No. 3 ornithine citrulline arginine

  9. No. 4 cysteine     No. 5  homoserine Unknown Pathway 1 3 2 4 4 No. 2 No. 3 No. 1 cystathionine homocysteine methionine

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