Flashcards in Glycogen and Pentose Phosphate Pathway Deck (15):
Muscle can burn either _________.
glucose or fat
Glucagon and epinephrine lead to an increase in intracellular ______ that activates ________. That enzyme, when activated, phosphorylates ________.
cAMP; PKA; glycogen phosphorylase kinase (activating it)
Glycogen phosphorylase kinase and glycogen phosphorylase are both activated by ___________. They work to break down glycogen.
being phosphorylated (which occurs in response to epinephrine, cortisol, glucagon, and growth hormone)
____________ synthesis is inhibited by phosphorylation.
Muscle glycogen stores can be exhausted in _________ of vigorous activity.
less than an hour
Which enzyme converts glucose 6-phosphate to glucose 1-phosphate in the glycogen synthesis pathway?
Glycogen synthase adds glucose to the ______ end of glucose.
How can defects in glycogen synthesis simultaneously cause hepatomegaly and hypoglycemia?
If cells lack proper branching enzymes (utilized in glycogen synthesis), then they will have larger than normal stores of glycogen but be unable to use them quickly.
Glycogen phosphorylase converts glycogen to _________.
The key stimulator of glycogen synthase and inhibitor of glycogen phosphorylase in the liver is __________.
How does intracellular calcium lead to glycogen breakdown?
Calcium binds to calmodulin which then activates glycogen phosphorylase kinase which phosphorylates glycogen phosphorylase (thus activating it); alternatively, PKA can also phosphorylate glycogen phosphorylase kinase.
AMP also allosterically activates glycogen phosphorylase.
How is active phosphorylase kinase turned off?
Protein phosphatase (stimulated by insulin)
PKA phosphorylates and thus _________ glycogen synthase.
The first enzyme in the pentose monophosphate pathway is _______________.
glucose 6-phosphate dehydrogenase