Download Glycogenesis - COFFEE BREAK CORNER

Glycogenesis Definition Site Chemistry Steps Glycogen synthesis Liver , muscle Homopolysaccharide Glucokinase, hexokinase mutase G G6P G1P Glucose synthase ( α1-­‐4) Elongation of chain till 10 -­‐12 glucose UDPG + Glycogen primer Branching enzyme (α1-­‐6) Glycogen Regulation ♣ Insulin, G6P, glucose à stimulate glycogenesis ♣ Glucagon, epinephrine àinhibit glycogenesis Key enzyme ♣ Glycogen synthase ♣ Branching enzyme Glycogenolysis Definition Site Steps Breakdown of glycogen Liver, kidney Glycogen Debranching enzyme Transferase enzyme Phosphorylase enzyme Key enzyme Regulation G1p G6P Glucose Glycogen phosphorylase enzyme Debranching enzyme ( glucotransferase ) Hormonal 1. Epinephrine : ++ glycogenolysis -­‐-­‐-­‐ glycogenesis 2. Glucagon : ++ glycogenolysis -­‐-­‐-­‐ glycogenesis 3. Insulin : ++ glycogenesis -­‐-­‐-­‐ glycogenolysis Differences between muscle and liver glycogen Liver glycogen Muscle glycogen Amount Liver has more conc. Muscle has more amounts. Sources Blood glucose and other radicals Blood glucose only Hydrolysis Give blood glucose Due to absence of phosphatase enzyme not give free glucose but give lactic acid Starvation Changes to blood glucose Not affected Muscular ex. Depleted Depleted Hormones Insulin → ↑↑ it Insulin → ↑↑ Adrenaline → ↓↓ Adrenaline → ↓↓ Thyroxine → ↓↓ Thyroxine → ↓↓ Glucagons → ↓↓ Glucagons → no effect due to absence of its receptors Control of Glycogen Metabolism:
A highly regulated process, involving reciprocal control of glycogen phosphorylase and glycogen synthase
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GP allosterically activated by AMP and inhibited by ATP, glucose-6-P and caffeine
GS is stimulated by glucose-6-P
Insulin is secreted from the pancreas (to liver) in response to an increase in blood glucose
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Insulin stimulates glycogen synthesis and inhibits glycogen breakdown
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Glucagon and epinephrine stimulate glycogen breakdown
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Glucagon acts in liver and adipose tissue only!
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Epinephrine acts on liver and muscles