Glycogen Flashcards
When is glycogen used?
in the gap between the fall of the blood glucose after a meal and the start of gluconeogenesis
where are the main stores of glycogen?
liver + skeletal muscle
what are the 2 types of glycosidic bonds that are found in glycogen?
Alpha (1-4) linkage
Alpha (1-6) linkage [branching one]
what enzyme will elongate glycogen chains?
glycogen synthase
why are branches important in glycogen?
they provide additional ends for synthesis and breakdown
what enzyme creates branches in glycogen?
branching enzyme
what is the rate limiting step in the degradation of glycogen?
PLP in the conversion of glycogen to glucose 1-P
what enzyme breaks down glycogen in the lysosomes?
lysosomal alpha (1-4) glucosidase
what two enzymes are the regulatory enzymes for glycogen synthesis and degradation?
glycogen synthase
glycogen phosphorylase
what up regulates/ activates glycogen synthase in the liver and muscle?
insulin
what deactivates glycogen synthase in muscle?
epinephrine
what deactivates glycogen synthase in the liver?
glucagon
epinephrine
what activates glycogen phosphorylase in the liver?
glucagon
epinephrine
what activates glycogen phosphorylase in muscle?
epinephrine
AMP
Ca2+
what deactivates glycogen phosphorylase in liver and muscle?
insulin
what deficiency is Von Gierke?
G6PD
What are the 6 key symptoms of Von Gierke?
severe fasting hypoglycemia lactic acidosis (fasting) hepatomegaly hyperlipidemia hyperuricemia short stature
what is a common secondary symptom from the hyperuricemia in Von Gierke ?
Gout
What is the lactic acidosis from in Von Gierke?
buildup of G6PD stops gluconeogenesis
formation of lactate from pyruvate is favored and lactate from RBCs cannot be used for gluconeogenesis
what is the deficiency in Pompe?
lysosomal alpha 1-4 glucosidase deficiency
what is the deficiency in Cori Disease?
debranching enzyme
what are the symptoms in Cori Disease?
mild hypoglycemia
liver enlargement
what is the deficiency in Anderson disease?
branching enzyme
what are the 3 key symptoms in Anderson disease?
infantile hypotonia (low muscle tone) cirrhosis early death (liver and hear severely damaged)
what is the deficiency in McCardle disease?
muscle glycogen phosphorylase
what are the 2 key symptoms of mccardle disease?
muscle cramps and weakness on exercise
myoglobinuria
what is the deficiency in Hers disease?
liver glycogen phosphorylase deficiency
what are the key symptoms of Hers disease?
mild fasting hypoglycemia
hepatomegaly
cirrhosis
