Glycogen Flashcards
What are the Energy sources of glucose?
brain, blood cells, exercising muscle
What are our sources of glucose?
Diet
glycogen
gluconeougenesis
How quickly does Gluconeogenesis respond when glucose is needed?
it has a slow response
What can glycogen do when we have low blood sugar?
glycogen in liver and kidney can breakdown and release glyucose quickly
what can glycogen do in exercising muscle?
glycogen in muscle can breakdown and release glucose for energy
What is the storage form of carbohydrates in humans?
glycogen
What kind of bonds does Maltose contain?
alpha(1->4) Bond between two glucose molecules
What are the primary storage sites of Glycogen?
liver and skeletal muscle
What forms the chains in glycogen?
alpha (1->4) bonds (a glycosidic bond)
What kind of are the branch points in glycogen?
alpha(1->6) bonds (a glycosidic bond)
What bonds does glycogen contain?
branched are alpha (1->6)
chains are alpha(1->4) bonds
when does branching occur in glycogen?
approximately every 10 glucose molecule
What is the purpose of branching in glycogen?
provides increased solubility
provides easier access to glucose
What is the cellular location of glycogen?
the cytosol
How do we convert glycogen into Glucose-1-phosphate?
with glycogen phosphorylase and coenzyme-pyridoxal phosphate
What is the product of this reaction: Glycogen —-Glycogen phosphorylase+ Coenzyme-pyridoxal phosphate –> ???????????
Glucose-1-phosphate
How is glucose-1-phosphate converted into glucose-6-phosphate
with the enzyme Phosphoglucomutase
Why is glucose trapped in muscle?
muscle lacks the enzyme to release glucose
What happens to glucose-6-phosphate in the liver?
endoplasmic reticulum (idk??)
It’s converted to free glucose
Glucose is sent to cytosol
What turns glucose-6-phosphate into free glucose?
glucose-6-phosphatase
When glucose-6-phosphate is sent to the cytosol in the liver what is done to the glucose?
glucose-6-phosphate is released into the blood stream
What happens to glucose-6-phosphate when send to the muscle?
glucose-6-phosphate goes through glycolysis
when is phosphorylase no longer effective at breaking down glycogen?
when there are four glucose molecules left prior to a branch point
What two enzymes are required to breakdown a branch point in glycogen?
glucosyl-(4:4)-transferase
Amylo-alpha-(1,6)-glycosidase
What does glucosyl-(4:4)-transferase do?
Removes the outer three glucose molecules prior to a branch point in glycogen
What does Amylo-alpha-(1,6)-glycosidase do?
Removes the last glucose molecules prior to branch chain in glycogen
What is the main enzyme in glycogenolysis regulation?
glycogen phosphorylase
what stimulates glycogenolysis?
Liver (Fasting stimulates)
Muscle (stimulated during exercise)
What are the hormonal regulation of glycogenolysis?
Glucagon (in liver)
Epinephrine (in liver/muscle)
activation of adenylyl cyclase happens in response to what in glycogenolysis?
cAMP
Protein kinase A (PKA)
(ASK?)
To what other hormone does Catecholamines work similar to?
Glucagon
What regulates glycogen regulation?
Low blood glucose Epinephrine Calcium ADP, AMP Low energy charge
Why is calcium released in muscle for glycogen degradation?
neural stimulation - releases Ca2+ from sarcoplasmic reticulum
Why is Calcium released in liver?
epinephrine (unsure on how to phrase q)
When Calcium binds to calmodulin (CaM) what happens?
It forms the CA2+-CaM complex and activates phosphorylase kinase
Ca2+ and stress (don’t know how to phrase)
Liver
Epinephrine release from adrenal medulla (need glucose)
Releases Ca2+ from ER to cytoplasm (binds to CaM)
Ca2+-CaM activates phosphorylase kinase
What happens when AMP binds to glycogen phosphorylase “b”?
no phosphorylation will occur
What are the Enzymes used in glycogen breakdown?
Glycogen phosphorylase Phosphoglucomutase Glucosyl-(4:4)-transferase Amylo-alpha-(1,6)-glucosidase Glucose-6-phosphatase
