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Lecture 14 Slides rh
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Glycogen: the glucose buffer…
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Glycogen granules ~ 1600 glucose monomers per granule
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fig 7-14
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Glycogen in real life…
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How is glycogen synthesized?
-sequential addition of glucose to a growing a1-4 linked linear polymer glycogenin, then glycogen synthase -creation of branches composed of a1-6 linkages branching enzyme
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Glucose ends… O 1 2 3 4 5 6 non- reducing end reducing end
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polymer ends… fig 7-14
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pg 597
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addition of UDP carrier to glucose-1-P
fig 15-29
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addition of glucose monomers to the growing glycogen chain
fig 15-30
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Glycogen branching enzyme creates branches
fig 15-31
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Glycogen branching enzyme creates branches
10 a1 4 3 7 a1 6 fig 15-9
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How is glycogen broken down?
-sequential removal of glucose-1P from the non-reducing end glycogen phosphorylase -dismantling of those pesky branches debranching enzyme
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fig 14-11
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debranching enzyme removes branches fig 15-26
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7 4 7 1 Debranching enzyme removes branches a1 4 a1 6 a1 4 a1 4 a1 6
free glucose 4 a1 6 a1 4 7 a1 4 1 a1 6 transferase activity a1-6 glucosidase
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Allosteric control of glycogen phosphorylase
fig 15-36
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Hormonal control of glycogen phosphorylase
fig 15-34
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regulation of glycogen synthase by phos- phorylation as well… fig 15-37
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Liver glucose metabolism fig 23-13
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Blood glucose level is critical and stringently regulated fig 23-23
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The Cori cycle fig 23-20
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Liver as a "glucostat" low blood glucose high blood glucose
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Glucagon: the hormone of starvation
phosphorylation of enzymes alteration of fructose 2,6 bis P
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Insulin: the hormone of plenty
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fig 23-24
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b cell glucose sensing: an ATP gated channel
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