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Glycogen Metabolism
Medical School Biochemistry
15
Biochemistry
Graduate
10/05/2011

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Cards

Term
What is the first step of Glycogenolysis?
Definition
Glyogen -> Glucose 1-Phosphate

via Phosphorylase
Term
What is the second step of glucogenolysis?
Definition
Glucose 1-phosphate -> Glucose 6-phosphate

via phosphoglucomutase
Term
What is the final step of glycogenolysis in the liver?
Definition
Glucose 6-phosphate -> Glucose

via Glucose 6-phosphatase
Term
What is the final step of glycogenolysis in the muscles?
Definition
Anaerobic metabolism of glucose. Yields 2 lactate and ATP
Term
What kind of bonds can phosphorylase cleave?
Definition
Alpha 1-4 bonds
Term
How are branched chains dealt with in glycogenolysis? How does this work?
Definition
With the debranching enzyme

The debranching enzyme has two steps
1) 1-4:1-4 transferase activity (leaving only the alpha 1-6 bond)

2) alpha 1-6 glucosidase activity (cleaving leftover alpha 1-6 bond)
Term
What is the fist step of Glycogenesis?
Definition
Glucose -> Glucose 6-phosphate

via Glucokinase (liver) Hexokinase (muscle)
Term
What is the second step of Glycogenesis?
Definition
Glucose 6-phosphate -> Glucose 1-phosphate

via Phosphoglucomutase
Term
What is the third step of Glycogenesis?
Definition
Glucose 1-phosphate -> UDP-glucose

via UDP-glucose pyrophosphorylase
Term
What is the final step of Glycogenesis?
Definition
UDP-glucose -> Glycogen

via Glycogen Synthase
Term
What kind of bonds can Glycogen synthase form?
Definition
Alpha 1-4
Term
How are branched chains synthesized in glycogen? What enzyme is responsible?
Definition
Branching enzyme

has a 1,4:1,6 transferase activity that allows for the necessary branching to occur
Term
What is the presentation and deficient enzyme of a Type I Glycogen Storage Disease (Von Gierke)
Definition
Glucose-6 phosphatase

Presentation: sever hypoglycemia, lactic acidosis, hepatomegaly, hyperlipidemia, hyperuricemia, short stature, doll-like facies, protruding abdomen, and emaciated extremities
Term
What is the deficient enzyme and clinical presentation of a patient with a type II glycogen storage disease (Pompe)
Definition
Lysosomal alpha1,4-glucosidase

presentation: cardiomegaly, muscle weakness

prognosis: death by two years
Term
What is the deficient enzyme and clinical presentation of a patient with a type V glycogen storage disease (McArdle)?
Definition
Muscle glycogen phosphorylase

presentation: muscle cramps and weakness on strenous exercise, myoglobinuria
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