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molecular revolution

molecular revolution. The first molecular markers: allozymes. Allozymes Enzymes that diifer in amino acid sequence yet catalyze the same reaction -visible as a band on a gel -may exist at several gene loci Isozyme: allelic form of allozyme (same locus). +. enzyme. Visible

magdalena-fajardo
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molecular revolution

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  1. molecular revolution

  2. The first molecular markers: allozymes Allozymes Enzymes that diifer in amino acid sequence yet catalyze the same reaction -visible as a band on a gel -may exist at several gene loci Isozyme: allelic form of allozyme (same locus)

  3. + enzyme Visible Product - Substrate Allozyme assay • Gel electrophoresis • Current • Charge • Gel matrix • Starch or other medium • Protein variation • Charge • depends on pH • Size • different length of AA chain • Shape • Tertiary and quaternary structure • Visualization • Uses enzyme reactions • Specific substrate for each allozyme

  4. Lab assay of isozymes

  5. Isozyme gels

  6. Quaternary Structure and Allozymes Genotype AA AB BB • Enzymes can consist of several subunits • Monomer • One subunit • Dimer • Two subunits • Tetramer • Four subunits

  7. Disparate viewpoints about true levels of genetic variation • classical + + + m + ... + + + ============== + + + + + ... + + + • balanced A1 B2 C3... X1 Y1 Z3 ================= A4 B2 C7... X1 Y1 Z2 Allozymes revealed unexpectedly high levels of genetic variation

  8. Allozyme questions • What type of DNA variation can you detect with isozymes? • What is the ascertainment bias? • Why were they wildly popular in the 1970’s and 1980’s, then disappeared by 2000?

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