E2 Glycogenolysis (1/2 Bobby) Flashcards
What are the 2 primary storage sites of glycogen?
- Liver
2. Skeletal muscle
What type of glycosidic bond forms chains? Branch?
Alpha (1-4)
Alpha (1-6)
Where is glycogen stored in the cell?
Cytosol
What supplies glucose to the brain?
Liver (glucose to brain b/w meals)
What is the purpose of glycogenolysis in
A. Muscle
B. Liver
A. Energy
B. Blood glucose homeostasis
T/F. Gluconeogenesis is faster than glycogenolysis.
False
What enzyme does glycogen phosphorylase require?
Pyridoxal phosphate (B6)
What type of bond does glycogen phosphorylase break?
Alpha (1-4)
What is the product of glycogen phosphorylase?
G-1-P
What enzyme facilitates G-1-P —> G-6-P?
Phosphoglucomutase
What is the fate of G-6-P in muscle?
Glycolysis
What enzyme facilitates G-6-P —> free glucose in the liver?
G-6-phosphatase
G-6-P can be ________ in the pentose phosphate pathway.
Oxidized
What is the key regulatory enzyme of glycogenolysis?
Glycogen phosphorylase
What is the fate of free glucose in the liver?
Sent to the cytosol and then to the blood
When will glycogen phosphorylase cease breaking alpha (1-4) bonds?
When it is 4 glucose residues away from branch point
Which enzyme removed outer 3 glucose molecules? (aka make longer chain)
Glucosyl (4:4) transferase
Which enzyme removes the last glucose of a branch?
Amylo-alpha (1,6)- glucosidase
After alpha (1-6) bond is broken in the muscle, it is phosphorylated via ________.
Hexokinase
MATCHING
A. Muscle B. Liver C. Glycogen phosphorylase B
D. Glycogen phosphorylase A E. R-state F. T-state
- Active form
- Inactive form
A. 2 B. 1 C. 2 D. 1 E. 1 F. 2
Will glucose binds to phosphorylase A in liver or muscle?
What happens to the state (R/T)?
Will it inhibit or stimulate glycogenolysis?
Liver
R state –> T state
Inhibit
T/F. Liver energy change impacts glycogenolysis.
False
T/F. Muscle energy change impacts glycogenolysis.
True
High [AMP] binds to phosphorylase B in liver or muscle?
What happens to the state (R/T)?
Will is inhibit or stimulate glycogenolysis?
Muscle
T state –> R state
Stimulate
High [ATP] binds to phosphorylase B. Will it inhibit or stimulate glycogenolysis?
Inhibit
High [G-6-P] binds to phosphorylase B. Will is inhibit or stimulate glycogenolysis?
Inhibit
T/F. Glycogen phosphorylase B reminds inactive until stimulated.
True
Type of competition between G-6-P and ATP in skeletal muscle?
Allosteric
What two hormones will stimulate the CAMP cascade?
Epinephrine and Glucagon
When will epinephrine be released in response to?
Fear and Exercise
What tissue will you primarily find epinephrine?
Muscle
When will glucagon be released in response to?
Low blood sugar
What tissue will you find glucagon?
Liver
T/F. Epinephrine and Glucagon both stimulate the CAMP cascade, which will eventually phosphorylate the enzyme, converting it from glycogen phosphorylase a —> b.
False; glycogen phosphorylase b —> a
In covalent modification regulation using the CAMP cascade, what enzyme must be phosphorylated and activated?
Glycogen phosphorylase kinase
Once glycogen phosphorylase kinase is activated, what enzyme will activated? What happens to phosphorylase B/A?
Glycogen phosphorylase
phosphorylase b –> phosphorylase a
What enzyme is a second messenger for the CAMP cascade?
Adenylyl cyclase
What is the subunit for glycogen phosphorylase kinase?
Calmodulin
T/F. When calcium binds to calmodulin forming the Ca2+-calmodulin complex, glycogen phosphorylase kinase will be inhibited, therefore activating glycogen breakdown.
False; activate glycogen phosphorylase kinase
In the muscle, what will trigger the release of Ca2+ from the sarcoplasmic reticulum?
Muscle contraction
In the liver, what will trigger the release of Ca2+?
“Fight or Flight” response
Once energy or glucose needs have been satisfied (glucagon and epinephrine no longer present), CAMP is converted to _________ and no longer activates _________.
Converted to AMP
No longer activated PKA
What enzyme removes the phosphate group from glycogen phosphorylase converting it back to an inactive form?
Protein phosphatase1 (PP1)
What is the storage location of glycogen in the brain?
Astrocytes (adults) and Embryonic neurons
T/F. The highest concentration of glycogen in the brain is where there is the least amount of synaptic activity.
False
_____ matter has 2x’s the amount of glycogen concentration than _____ matter.
Gray, White
T/F. Glycogen metabolism regulation in the brain is similar to that in the liver and skeletal muscle via allosteric regulation, Ca2+, AMP, and epinephrine/norepinephrine.
True
What four factors will stimulate glycogenolysis?
- low energy
- epinephrine/norepinephrine
- Glucagon (low glucose)
- Calcium (m. contraction or stress)
T/F. The same environment as glycogenolysis will stimulate glycogenesis.
False; opposite environment
