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27 Cards in this Set

  • Front
  • Back
what specific bond is associated with branching on a glycogen molecule?
alpha-1,6-glycosidic bond
branching on a glycogen molecule occurs at approximately every ______ glucose monomers.
8 to 14
in the first step of glycogen synthesis, glucose-1-P goes to UDP-glucose via what enzyme and cofactor?
UDP-glucose pyrophosphorylase and UTP
are the 2 Phosphates on UDP-glucose both from UTP?
No, one is from UTP and the other remains from glucose-1-P.
what, self-glycosylating, protein forms the initial glucose monomer chain from which glycogen can be formed?
what enzyme acts to add UDP-glucose to the growing glycogen chain?
glycogen synthase
is UDP-glucose added to the non-reducing or reducing end of the glycogen template?
non-reducing end
what action the the 'branching enzyme' perform? be specific
-a 7 segment section is transferred from the non-reducing endof a chain to the C6-hydroxyl group on the same or another glycogen molecule.
-every segment transferred comes from a chain at least 11 residues long.
-branching point must be at least 4 residues from all other branches
In regards to glycogen degredation, what are the yeilded percentages of glucose-1-P to free glucose?
90% G-1-P to 10% free glucose
wat is the action of 'glycogen phosphorylase'?
-causes the cleavage of alpha-1,4-linked residues yeilding G-1-P + Gly(n-1).
-continues cleavage until at least 5 residues from a branching point.
what is the mechanism of action of the 'debranching enzyme'?
-first, the enzyme transfers the last three residues on the branch chain to the non-reducing end of another glycogen molecule.
-then, the enzyme cleaves the alpha-1,6-glycosidic linkage to yeild free glucose + debranched glycogen.
How many active sites does the 'debranching enzyme' have?
2 active sites
what are the allosteric effectors of 'glycogen phosphorylase'? how do they effect the enzyme?
activator: AMP, (phosphorylation)

inhibitors: ATP, Glucose-6-P, free glucose.
what are the allosteric effectors of 'glycogen synthase'? how do they effect the enzyme?
activators: ATP, liver glucose, gucose-6-P.

inhibitor: (phosphorylation)
glucogon binds to a cell surface receptor protein which is a member of a group of proteins called, _____.
the G-protein receptor of glucagon activates what enzyme?
adenylate cyclase
adenylate cyclase aids in the synthesis of what molecule?
what group of proteins does cAMP phosphorylate and activate?
"cAMP dependant protein kinases"
cAMP dependant protain kinases phosphorylate and activate what two enzymes?
phosphorylase kinase and PPI-1 (phosphoprotein phosphatase inhibitor-1)
'phosphorylase kinase' phosphorylates what two enymes with what effect?
glycogen synthase (inactivates)

glycogen phosphorylase (activates)
what two effects do the actions of action of phsphorylase kinase have which together have an additive effect.
it activates glycogen degredation at the same tome as it inhibits gycogen synthesis.
-this ensures a unidirectional path.
Ca+ inds to what subunit of the phosphorylase kinase enzyme? what affect does this have?
binds to 'calmodulin' subunit. results in increased enzyme activity.
(binding of AMP also causes increased activity...)
what glucose transporter is activated by insulin? where is it present? how is it stored?
GLUT-4. present in muscle and adipose tissue. stored in intracellular vesicles.
what two effects does insulin binding to muscle cells have on the glucose transporter GLUT-4?
stimulates its release from intracellular vesicles and also INCREASES its Vmax.
what effect does insulin binding have on 'phosphodiesterase'? what does this enzyme do?
activates phosphodiesterase which in turn degrades cAMP.
what effect does insulin have on 'phosphoprotein phosphatase-1 (PP-1)? what does this enzyme do?
activates the enzyme which leads to the Dephosphorylation of: phosphorylase kinase, glycogen synthase, glycogen phosphorylase and PPI-1
which enzyme of gluconeogenesis is effected by insulin? how?
insulin leads to the inactivation of PEPCK.