Biochem - Glycogen Flashcards

1
Q

Draw out glycogenesis pathway

A

Page 539

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2
Q

Draw out glycogenolysis pathway

A

Page 539

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3
Q

McArdle disease – Type V

A

Glycogen phosphorylase deficient
Muscle cells accumulate glycogen
-> water influx -> lyse

cause Rhabdomyolysis -> myoglobulinuria, renal failure

muscle cramping
normal life expectancy

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4
Q

Von Gierke disease (type I)

A

Glucose 6 phophatase deficiency
-liver, enterocytes, kidney

severe fasting hypoglycemia
glycogen buildup in liver -> hepatomegaly

enlarged kidneys
elevated serum lactate
elevated uric acid
Hypertriglyceridemia

Tx: frequent meals, cornstarch at night

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5
Q

Cori disease (typeIII)

A

Alpha-1,6-glucosidase deficiency

Can’t break down 1,6; but can break down 1,4 linkages

Milder hypoglycemia

No elevation of lactate level
No elevation of uric acid

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6
Q

Pompe disease – deficiency

A

Deficiency of alpha-1,4-glycosidase in lysosomes

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7
Q

Pompe disease infantile form

A

No enzyme activity
Severe muscle weakness
Cardiomegaly and heart failure
Shortened life expectance less than 1 yr untx

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8
Q

Pompe disease adult form

A
Some enzyme activity
No cardiac involvement
Gradual onset of sk.m. weakness
Diaphragm weakness
Respiratory failure
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9
Q

Alpha 1,6 glucosidase activity

A

Part of glycogenolysis pathway

Transferase activity:
4 alpha d-gluconotransferase
-3 of last 4 glucose molecules left by glycogen phosphorylase transferred to another chain

Alpha 1,6 glucosidase activity removes last glucose molecule of branch.

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10
Q

Glycogen regulation

A

Insulin: inhibits glycogen phophorylase – stimulate glycogen synthesis

High stress tate: epi and glucagon release – counter regulatory hormones

Glucagon: stimulates adenylyl cyclase -> cAMP -> PKA ->
Glycogen phophorylase kinase -> glycogen phosphorylase -> glycogenolysis

Epinephrine:
b-adrenergic receptors stimulates adenylyl cyclase -> glycogen phosphorylase -> glycogenolysis

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