Glycogen synthesis Flashcards
What is the storage form of carbohydrate in animals
Glycogen
What are the primary storage sites of glycogen
Liver and skeletal muscle
What bonds are associated with the chain portion of glycogen
a(1-4)
What bonds are associated with the branch portion of the glycogen
a(1-6)
how often does glycogen branch
every 10 glucose
What is the maximum amount of glucose on a glycogen molecule
55,000
What form of glycogen is synthesized more rapidly following post exercise
Proglycogen
What form of glycogen is responsible for carbohydrate loading
Macroglycogen
What form of glycogen is synthesized for at least 48 hours post exercise
Macroglycogen
How many grams of glycogen can muscles store
400 grams
How many grams of glycogen can liver store
100 grams
Can skeletal muscle release glucose
No, but the liver can
Where in the cell is glycogen stored
Cytosol
what are the steps in making glycogen
Phosphorylate glucose make UDP glucose Initiation Elongation Branching
What enzyme is used to phosphorylate glucose
Hexokinase (muscle)
Glucoginase (liver)
What anzyme is used to make UDP-glucose
pyrophosphatase
What happens in the initiation step
connect glucose to glycogenin
What enzyme elongates the glycogen chain by adding on glucose
Glycogen synthase
Starting with glucose what is it turned into to get to UDP glucose
Glucose Glucose 6P Glucose 1P Glucose UTP Glucose UDP
What enzyme connects glucose to glycogenin and is responsible for initiation of glycogen synthesis
Glycogen initiator synthase
How much ATP is used to attach glucose to glycogen
3 ATP
What enzyme is responsible for forming the branches in glycogen
Glucosyl 4:6 Transferase
What are the main enzymes of glycogen synthesis
Glycogen synthase (makes glycogen) Glycogen phosphorylase (glycogen-->glucose)
What stimulates glycogen synthesis
High ATP
High Glucose
Insulin
Low glycogen
What stimulates glycogen phosphorylase (inhibit glycogen synthase)
Low ATP High ADP or AMP Low Glucose Glucagon Muscle contration (calcium)
What is a more potent regulator of glycogen synthase activity. Muscle glycogen concentration or insulin or muscle contration
Muscle glycogen concentration
What happens to glycogen synthesis and insulin sensitivity post exercise
Increase
What types of muscle fibers use up the most muscle glycogen
Type II fibers
When is glycogen synthesis at its highest post exercise
30 min
how much is glycogen synthesis reduced by 120 min after exercise
about 1/9th
When is the rapid phase of glycogen synthesis
30-60 min post exercise
What phase (rapid/slow) of glycogen synthesis is insulin independent
Rapid phase
What needs to happen in order for the rapid phase of glycogen synthesis to occur
Low muscle glycogen levels
Carbs provided immediately after exercise
What must the slow phase of glycogen synthesis have for it to happen
Carbohydrates and insulin
How long does the slow phase (insulin dependent) last
3-48 hours after exercise
What does adding carbohydrates post exercise do to glycogen synthesis
Increase insulin
Small increase in glycogen synthase activity.
if post exercise carbohydrae ingestion is delayed by 2 hours, what is the decrease of glycogen synthesis rate
45% lower
This is not glycogen synthases activity it is the overall glucose to glycogen rxn
What will be catabolized to make glycogne if you do not eat after exercise
Catabolize AA to make glycogen
What effect does the ingestion of amino acids have on glycogen synthesis
increase synthesis rate
Does the addition of amino acids have an effect on glycogen synthesis when carb intake is hight (above 1.2 g/kg/h)
No it doesn’t
What type of protein has the greatest effect on muscle glycogen synthesis post exercise
Whey protein hydrosylates
Who has more glycogen synthesis post exercise. A trained or untrained individual
Trained individual
who has more glut4. Trained or untrained infividual
Trained individual
what is glycemic index
Increase in blood glucose level over the base-line level during a 2 hr period
What is glycemic load
the glycemic index times the amount of grams of carbohydrate in a serving of the food
What does a higher Glycemic load mean
greater expected elevation in blood glucose and in the insulinogenic effect of the food
What can a higher consumption of high glycemic load food cause
Type II dibetes
Obesity
When measuring in days compared to hours, are hi gi meals better than lo gi meals
There is no difference
When fed low GI meals what happens to blood glucose levels in the latter phases of exercise
It is higher
Low insulin during exercise allows for and increase in what
Free fatty acids
What causes a threefold increase in liver glycogen synthesis
low-dose fructose
How does low does fructose increase glycogen synthesis
increase glucose tolerance by activating glucokinase
in the fasted state what is the main endogenous source of glucose
the liver
What is the primary site of fructose disposal
The liver
What are the enzymes needed for fructose metabolism
Fructokinase
Triokinase
Does fructose increase glycogen synthesis in muscles
No
Does low blood glucose or glucagon cause muscle glycogen to break down
No
