Glycogen Degradation Flashcards
What uses glucose as an energy source
Brain
Blood Cells
Exercision Muscles
What are some sources of glucose
Diet
Glycogen
Gluconeogenesis
When will glycogen get broken down into glucose
Low Blood sugar
Exercising muscle
What bonds are found in the “CHAINS” of glycogen
a(1-4)
What bonds are found in the “BRANCHES” of glycogen
a(1-6)
When will you find a branch in glycogen
every 10 glucose
Why is glycogen branched
Increased solubility
Easier access to glucose
Where would you store glycogen
Cytosol
What compound is broken off of glycogen by glycogen phosphorylase
Glucose-1-phosphate
What is the first enzyme used in glycogen degradation
Glycogen phosphorylase
What enzyme turns glucose-1-phosphate into glucose-6-phosphate
phosphoglucomutase
When does glycogen phosphorylase stop being able to degrade glycogen
When there are 4 glucose m/c left prior to a branch point
What two enzymes are required to break down branches of glycogen
Glucosyl-4:4- Transferase
Amylo-a-1,6-glucosidase
What enzyme removes the outer 3 glucose molecules of glycogen at a branch site
Glucosyl-4:4-transferase
What enzyme removes the last glucose of glycogen at a branch site
Amylo-a-(1,6)-glucosidase
What hormones regulate Glycogenolysis
Glucagon
Epinephrine
What hormone regulates glycogenolysis in liver
Glucagon
Epinephrine
What hormone regulates glycogenolysis in muscles
Epinephrine
How does cAMP inactivate glycogen synthesis in the liver
cAMP activates Protein Kinase which inactivates Glycogen synthase a (turns it into Glycogen synthase b)
What is the inactive form of glycogen synthase a
Glycogen synthase b
How does cAMP activate glycogen break down in the liver
cAMP activates protein kinase which activates glygoen phosphorylase kinase which then activates glycogen phosphorylase b
What is the active form of glycogen phosphorylase b
glycogen phosphorylase a
does glucagon impact the liver or muscle
Muscle
What ion binds to calmodulin (CaM) to activate phosphorylase kinase
Calcium
How does calcium bind to CaM in muscles
Muscle contraction action potential has Ca in sarcoplasmic reticulum which binds to CaM
What enzyme is activated by the Ca-CaM complex
Phosphorylase kinase
How does Calcium bind to CaM in the liver
Epinephrine causes release of Calcium from ER into cytoplasm
What increases glycogen phosphoylase
Low ATP High ADP/AMP Low glucose Glucagon (live) Muscle contractions (calcium)
What increases glycogen synthase
Excess ATP
High levels of glucose
Insulin
Low glycogen
What are the enzymes involved in glycogen breakdown
Glycogen phosphorylase phosphoglucomutase glucosyl-4:4-transferase Amylo-a-1,6-glucosidase glucose-6-phosphatase
