Term
| What enzyme in glycogen synthesis is tightly regulated? |
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Definition
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Term
| What enzyme in glycogen degradation is tightly regulated? |
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Definition
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Term
| How is Glycogen Phosphorylase regulated? |
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Definition
| via a phosphorylation event, phosphorylated Glycogen Phosphorylase it is activated |
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Term
| What hormones upregulate action of Glycogen Phosphorylase? |
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Definition
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Term
| What is the mechanism by which Epinephrine and Glucagon upregulate Glycogen Degradation? |
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Definition
1) Hormones bind ligand
2) Activation of Adenylyl Cyclase System
3) cAMP
4) Activation of cAMP dependent protein kinase A (PKA)
5) PKA phosphorylates (activates) Glycogen phosphorylase kinase A
6) Glycogen Phosphorylase kinase A phosphorylates (activates) Glycogen Phosphorylase |
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Term
| What are the two ways that Glycogen phosphorylase Kinase can be activated (upregulating Glycogen degradation)? |
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Definition
| Via either PKA or intracellular calcium |
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Term
| What hormone downshifts the action of Glycogen phosphorylase? |
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Definition
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Term
| How does Insulin down regulate Glycogen degradation? |
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Definition
| By activating protein phosphatase 1 which dephosphorylates Glycogen phosphorylase |
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Term
| What are the two ways that Glycogen phosphorylase can be activated? |
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Definition
Phosphorylation event (through adenylyl cyclase system)
via high levels of intracellular AMP |
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Term
| How is Glycogen Synthesis inhibited? |
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Definition
| phosphorylation event on Glycogen synthase |
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Term
| What hormones inhibit Glycogen Synthesis? |
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Definition
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Term
| What is the mechanism by which Glycogen Synthase is inhibited? |
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Definition
1) hormones binds to receptor
2) adenyly cyclase system activated
3) cAMP
4) PKA
5) Phosphorylation (deactivation) of Glycogen Synthase |
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Term
| What hormone upregulated Glycogen synthesis? |
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Definition
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Term
| What is the mechanism by which Glycogen Synthase is upregulated? |
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Definition
1) Insulin activates Protein phosphatase
2) Protein phosphotase 1 dephosphorylates (activates) glycogen synthase |
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Term
| How does high inter cellular Glucose affect Glycogen regulation? |
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Definition
High levels of liver Glucose inhibit Glycogen degredation
In a similar vein, phosphorylated (trapped) hepatic Glucose (Glucose 6-phosphate) will stimulate Glycogen synthesis and downregulate Glycogen degradation |
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Term
| How does ATP affect Glycogen synthesis/degradation? |
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Definition
| ATP down regulates Glucose degradation |
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