BIOCHEM 385 EXAM 2 questions and
correct answers graded
Glycogen is degraded to yield ___________, which is isomerized to ___________. - correct
answer ✔✔-Glucose-1P
-Glucose-6P
What does glycogen phosphorylase do? - correct answer ✔✔Removes 1 glucose at a time from
non-reducing ends using organic phosphate (cleaves off last glucose)
What does glycogen synthase do? - correct answer ✔✔Adds glucose in a reaction involving
UDP-glucose.
Glycogen branching and deb ranching enzymes ensure what? - correct answer ✔✔That
glycogen phosphorylase and synthase have access to the maximum number of non-reducing
ends for cleavage or formation.
What does the glycogen branching enzyme do? - correct answer ✔✔Creates a new alpha-1,6
branch point and a new nonreducing end by transferring 7 glucose residues
Why is the inorganic phosphate used to generate glucose-1P when glycogen is degraded a free
inorganic phosphate? - correct answer ✔✔Because it does not require an ATP investment to
generate glucose-6P for glycolysis.
How many net ATP is required for glycogen synthesis per glucose added? - correct answer ✔✔1
ATP.
Non-reducing end of glycogen - correct answer ✔✔Glucose comes on and off of
,What does phosphoglucomutase do? - correct answer ✔✔Converts glucose-1-phosphate to
glucose-6-phosphate
What stimulates glycogen phosphorylase? - correct answer ✔✔Hunger (glucagon)
What stimulated glycogen synthase? - correct answer ✔✔Insulin
How does glucagon regulate glycogen metabolism? - correct answer ✔✔-Stimulates
phosphorylation reaction through glucagon receptor and PKA--> phosphorylates glycogen
phosphorylase (activates) and glycogen synthase (inactivates).
How does insulin regulate glycogen metabolism? - correct answer ✔✔-Stimulates de-
phosphorylation reaction through insulin receptor and protein phosphatase 1-->
dephosphorylates glycogen synthase (activates) and glycogen phosphorylase (inactivates).
Glucagon and epinephrine stimulate what? And what does it do? - correct answer ✔✔-
Phosphorylase kinase
-Phosphorylates and uses 2 ATP
Insulin stimulates what? And what does it do? - correct answer ✔✔-Protein phosphatase
-Takes a phosphate off
In muscle cells, before phosphorylase kinase kicks in, what causes the same conformational
change needed to activate glycogen phosphorylase? - correct answer ✔✔-AMP
-Once AMP is working, glucose displaces it and returns it to T form.
In muscle cells, before protein phosphatase kicks in, what causes the same conformational
change needed to inactivate glycogen phosphorylase? - correct answer ✔✔-Glucose
, -Still phosphorylated; glucose binding makes it inactive
What is the product of glycogen phosphorylase? What must happen for it to be useful? - correct
answer ✔✔-Glucose-1-phosphate
-Convert to Glucose-6P
What is the product of deb ranching enzyme? - correct answer ✔✔Glucose
How many ATP can be yielded from glycogen phosphorylase? - correct answer ✔✔3 ATP b/c
already added a phosphate
How many ATP can be yielded from debranching? - correct answer ✔✔2 ATP b/c a glucose
comes off and an ATP has to be used for hexokinase
Net phosphorylation drives glycogen ___________________, whereas net de-phosphorylation
drives glycogen ________________. - correct answer ✔✔-Degradation
-Synthesis
Allosteric regulators (AMP or glucose) _______________ drives glycogen phosphorylase activity,
whereas hormones _____________ reciprocal regulation. - correct answer ✔✔-Drives
-Sustain
What does glycogen degradation and synthesis accomplish in animals? - correct answer ✔✔-
Liver glycogen is used as a short-term energy source for the organism by providing a means to
store and release glucose in response to blood glucose levels.
-Muscle glycogen provides a readily available source of glucose during exercise to support
anaerobic and aerobic energy conversion pathways w/in muscle cells.
correct answers graded
Glycogen is degraded to yield ___________, which is isomerized to ___________. - correct
answer ✔✔-Glucose-1P
-Glucose-6P
What does glycogen phosphorylase do? - correct answer ✔✔Removes 1 glucose at a time from
non-reducing ends using organic phosphate (cleaves off last glucose)
What does glycogen synthase do? - correct answer ✔✔Adds glucose in a reaction involving
UDP-glucose.
Glycogen branching and deb ranching enzymes ensure what? - correct answer ✔✔That
glycogen phosphorylase and synthase have access to the maximum number of non-reducing
ends for cleavage or formation.
What does the glycogen branching enzyme do? - correct answer ✔✔Creates a new alpha-1,6
branch point and a new nonreducing end by transferring 7 glucose residues
Why is the inorganic phosphate used to generate glucose-1P when glycogen is degraded a free
inorganic phosphate? - correct answer ✔✔Because it does not require an ATP investment to
generate glucose-6P for glycolysis.
How many net ATP is required for glycogen synthesis per glucose added? - correct answer ✔✔1
ATP.
Non-reducing end of glycogen - correct answer ✔✔Glucose comes on and off of
,What does phosphoglucomutase do? - correct answer ✔✔Converts glucose-1-phosphate to
glucose-6-phosphate
What stimulates glycogen phosphorylase? - correct answer ✔✔Hunger (glucagon)
What stimulated glycogen synthase? - correct answer ✔✔Insulin
How does glucagon regulate glycogen metabolism? - correct answer ✔✔-Stimulates
phosphorylation reaction through glucagon receptor and PKA--> phosphorylates glycogen
phosphorylase (activates) and glycogen synthase (inactivates).
How does insulin regulate glycogen metabolism? - correct answer ✔✔-Stimulates de-
phosphorylation reaction through insulin receptor and protein phosphatase 1-->
dephosphorylates glycogen synthase (activates) and glycogen phosphorylase (inactivates).
Glucagon and epinephrine stimulate what? And what does it do? - correct answer ✔✔-
Phosphorylase kinase
-Phosphorylates and uses 2 ATP
Insulin stimulates what? And what does it do? - correct answer ✔✔-Protein phosphatase
-Takes a phosphate off
In muscle cells, before phosphorylase kinase kicks in, what causes the same conformational
change needed to activate glycogen phosphorylase? - correct answer ✔✔-AMP
-Once AMP is working, glucose displaces it and returns it to T form.
In muscle cells, before protein phosphatase kicks in, what causes the same conformational
change needed to inactivate glycogen phosphorylase? - correct answer ✔✔-Glucose
, -Still phosphorylated; glucose binding makes it inactive
What is the product of glycogen phosphorylase? What must happen for it to be useful? - correct
answer ✔✔-Glucose-1-phosphate
-Convert to Glucose-6P
What is the product of deb ranching enzyme? - correct answer ✔✔Glucose
How many ATP can be yielded from glycogen phosphorylase? - correct answer ✔✔3 ATP b/c
already added a phosphate
How many ATP can be yielded from debranching? - correct answer ✔✔2 ATP b/c a glucose
comes off and an ATP has to be used for hexokinase
Net phosphorylation drives glycogen ___________________, whereas net de-phosphorylation
drives glycogen ________________. - correct answer ✔✔-Degradation
-Synthesis
Allosteric regulators (AMP or glucose) _______________ drives glycogen phosphorylase activity,
whereas hormones _____________ reciprocal regulation. - correct answer ✔✔-Drives
-Sustain
What does glycogen degradation and synthesis accomplish in animals? - correct answer ✔✔-
Liver glycogen is used as a short-term energy source for the organism by providing a means to
store and release glucose in response to blood glucose levels.
-Muscle glycogen provides a readily available source of glucose during exercise to support
anaerobic and aerobic energy conversion pathways w/in muscle cells.
