Quiz 3 Glycogen Synthesis (Glycogenesis) Flashcards
What acts faster when glucose is needed, Glycogenolysis or GNG?
Glycogenolysis
Two primary storage sites of glycogen?
Liver and skeletal muscle
For review…a branch occurs how many glucose apart? What type of bond?
10 glucose molecules…A(1-6) bond
Muscle or liver lack enzyme to release glucose? What enzyme?
Muscle, glucose-6-phosphatase
Glycogenesis is initiated by?
Glucose-6-phosphate
If no glycogen fragment available, what begins the glycogen chain?
Glycogenin
Enzyme which starts the glycogen chain with amino acid tyrosine
Glycogen initiator synthase
How many ATP used to make glucose-6-phosphate?
1
Reactants of Phosphoglucomutase?
Glucose-6-phosphate
Products of Phosphoglucomutase?
Glucose-1-phosphate
What breaks apart pyrophosphate when making UDP-glucose?
Pyrophosphatase
What high energy compound is used to make UDP-Glucose?
UTP (uridine triphosphate)
What are the reactants of UDP-glucose Pyrophosphorylase?
UTP + Glucose-1-phosphate
What are the products of UDP-glucose Pyrophosphorylase?
PPi + UDP-Glucose
How many high energy molecules are used to synethsize glycogen?
3
What occurs during chain elongation? Where is this taking place in the cell?
Glucose is being added to chain, occurs in the CYTOSOL.
What enzyme is involved with Chain elongation? What types of bonds are being made?
Glycogen synthase, alpha (1-4) bonds
After ~ how many glucose added to the chain do we need to begin to branch?
7 (do not confuse this with the question earlier about how many glucose are in row until we find a branch which is 10)
Which enzyme is involved with branching and alpha (1-6) bonds?
Glycosyl-(4:6)-transferase
What is the key enzyme responsible for synthesis of glycogen?
Glycogen synthase
Allosteric regulation of glycogen synthase would be activated by?
glucose-6-phosphate
During exercise, is glycogenolysis or glycogenesis being active?
During exercise glycogenolysis (breakdown), and post exercise glycogenesis (synthesis)
If you phosphorylate glycogen synthase (hormonal regulation), will be it be active or inactive?
Inactive
Give examples of things that will inactivate glycogen synthase?
Glucagon, Epinephrine, norepinephrine
What will de-phosphorylate and active the enzyme?
Insulin
In other words, Glucagon would inhibit what and stimulate what?
Inhibit glycogen synthesis and stimulate glycogen breakdown
High ATP, High levels of glucose, Insulin, and low glycogen levels do what to glycogen synthase?
Stimulate
Primary site of fructose disposal?
liver
What are the two enzymes essential for fructose metabolism highly expressed in the liver?
Fructokinase, and Triokinase
Low-dose fructose causes what?
A threefold increase in net liver glycogen synthesis
Does fructose benefit muscle glycogen synthesis?
NOPE only live glycogen synthesis.
After intense exercise, glycogen synthesis happens at initially a high rate, it rapidly declines to about a 1/5th by 60 minutes and a 1/9th by 120 minutes. What are the two reasons for this?
Increased glucose uptake (GLUT 4) and increased enzyme activity (glycogen synthase)
What phase of glycogen synthesis is 30-60 mins after exercise and is insulin independent?
Rapid phase
After rapid phase, insulin dependent, and has a much slower rate of glycogen synthesis?
Slow phase
True or false, by increasing carb consumption, does it increase the rate of glycogen storage by more than 150%?
True
Incorporating ingestion of what along with moderate intake of carbs leads to higher muscle glycogen synthesis rates?
Proteins/amino acids
When enzymes of glycogen degradation or glycogen synthesis are defective and leads to increased storage but impaired breakdown?
Glycogen storage disease (GSD)
Most common GSD, is genetic, glucose – phosphatase deficiency (hypoglycemia)?
GSD type 1 or Von Gierk’s disease
