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2010-03-03 20:02:41
Glycogen Synth

Glycogen Synthesis
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  1. Descibe glycogen's structure.
    It is composed of mutiple glucose monomers, that have been connected with alpha - 1,4 glycosidic bonds or alpha - 1,6 glycosidic bonds. alpha 1,4 bonds create linear polymer chains and alpha 1,6 bonds create a branch point.

    It also has a linear structure that can be reduced by Cu2+. A glycogen chain has two ends, a reducing end (typically at C1) and a reducing end (typically at C4).

    In the Beta glycogen particle there are several "tiers" of glycogen chains (12-14 residues long). From the initial primer chain, branching points create secondary chains and so on. Beyond the fourth tier are out chains that don't experience branch points. The branching affect allows easier harvesting of glucose molecules when they are needed and maximizes the amount of glucose that can be stored as glycogen. As each tier is harvisted, subsiquent tiers become harder to harvest.
  2. Define the "non-reducing end."
    The "non-reducing end" is located at the C4 of a glucose molecule.
  3. What is the function of UDP-glucose pyrophosphorylase?
    UDP-glucose pyrophosphorylase is a key step in glycogen syth. It converts glucose-1-phosphate to UDP-glucose
  4. What is the function of glycogenin?
    Glycogenin is the structure that can add up to 8 glucose molecules to it self. It acts as the base of the reaction and the enzyme that catalyzes the rxn.
  5. What is the function of glycogenin synthase?
    It promotes the transfer of a glucose residue from USP-glucose to a nonreducing end of a branched glycogen molecule.
  6. What is the function of "branching enzyme?"
    When a glycogen chain reaches 11 residues long, the branching enzyme "counts" four glucose residuse at which point it cleaves the alpha-1,4 glycosidic bond and creates a branching point.