Glycogen Metabolism Flashcards
What is the stored form of carbs in animals and plants?
-Glycogen
-Starch
Which bonds are seen in glycogen?
alpha-1,4 and alpha-1,6
Where is the site of storage of glycogen and their significance?
1) Cytosol of liver
-Liver is the short term reserve used via glycogenolysis, works for 12-18hrs in fasting state, releases free glucose
2) Muscle, (brain minimal)
-lacks glucose-6-phospatase, so no free glucose is formed but glucose-6-phosphate is obtained, which is fuel for muscle contraction
-Glycogenin produces the first few glucose molecules
When does glycogenesis start?
After 18hrs
Why is liver “kind” and muscle “selfish”?
Muscle uses glycogen for itself but liver uses glycogen for the entire body
Which enzyme converts glucose to glucose-6-phosphate?
Hexokinase/glucokinase
Which hormone acts in glycogenesis?
Insulin
What enzyme converts Glucose-1-phos. to UDP-glucose?
UDP-glucose pyrophosphorylase
What is the enzyme that converts UDP glucose to alpha-1,4-linkage?
Glycogen Synthase
What is the rate limiting step of glycogenesis?
Glycogen synthase
Is alpha 1,4-linkage branched or unbranched?
Unbranched
What does glycogenesis do to Gs pathway?
Inactive it
What is glycogenin?
protein that form glycogen primer
Is alpha 1,6-linkage branched or unbranched?
Branched
What is the name of the branching enzyme and what step does it convert?
Amylo-1,4 to 1,6 transglucosidase
alpha-1,4-linkage to alpha 1,6-linkage
A deficiency of branching enzyme leads to which glycogen storage disease?
Anderson’s disease
Which hormone favors glycogenolysis?
Glucagon or epinephrine
Under what conditions does glycogenolysis occur?
Fasting state