Glycogen Metabolism Flashcards
UDP-glucose synthesis from ___ and UTP
Glucose 1-phosphate! It is isomerized from glucose 6-phosphate via Phosphoglucomutase
False about glycogenesis A)From molecules of α-D-glucose B)Site: cytosol of liver and muscles C)Stimulated by high amount of glucagon D)Energy sources: ATP and UTP
C)Stimulated by high amount of glucagon
Insulin dapat
UDP-glucose pyrophosphorylase, the enzyme that forms UDP-glucose, facilitates an irreversible reaction. True or false?
True. Synthesis of UDP-glucose is irreversible
This molecule, in absence of glycogen fragment…
Can accept glucose from UDP-glucose
Catalyzes the first few attachments itself
Site: Hydroxyl side-chain of a specific tyrosine
What is the molecule?
Glycogenin
Why is a primer needed for glycogen synthase to start?
It cannot bind free glucose to UDP-glucose
Glycogen synthase makes \_\_\_\_\_ bonds from the terminal end which receives glucose from UDP-glucose A)alpha (1-->6) B)alpha (1-->4) C)alpha (6-->1) D)alpha (4-->1)
B)alpha (1–>4)
What does nucleoside diphosphate kinase do?
Released UDP is phosphorylated to form UTP
[branch forming @ glycogen]
5-8 glucosyl residues are transferred from non-reducing end & are attached to another one in chain via ___
Alpha(1–>6) linkage
Primary product in glycogenolysis
Glucose 1-phosphate
What enzyme produces the primary product in glycogenolysis?
Glycogen phosphorylase
Glycogen phosphorylase requires ___ as coenzyme
Pyridoxal phosphate
End product of glycogen phosphorylase action
Limit dextrin
Removes the outer three of the four glucosyl residues attached at a branch, and transfers them to the non-reducing end of another chain
Glucosyl (4:4) transferase
Conversion of Glucose 1-phosphate to Glucose 6-phosphate c/o ___
Phosphoglucomutase
- A small amount of glycogen is continuously degraded by α (1–>4) glucosidase (acid maltase)
- Purpose of pathway is unknown
In what organelle does this occur?
Lysosome
Glycogen synthase is Allosterically (activated, inhibited) by glucose 6-phosphate
Activated
All activate glycogen phosphorylase except
A)ATP
B)glucose
C)AMP
C)AMP
Binding of any of the following EXCEPT ___ signals glycogen degradation to elevate blood glucose levels or to provide energy for exercising muscles
A)glucagon
B)insulin
C)epinephrine
B)insulin
•Insulin promotes overall increase in glycogen synthesis and decrease in degradation by increasing activity of what enzyme?
Protein phosphatase
