glycogen degradation Flashcards
what are chains of glucose connected by
a(1-4)
what are branches of glucose connected by
a(1-6)
how often does branching occur
every 10 glucose molecules
what does branching provide
increased solubility
easier access to glucose
maltose is a
a(1-4)
what the size of most granules
mid size
whats the maximal size of glucose molecules
55000
how many tiers of a carb
12
what does carb density increase
exponetially with each tier
non reducing ends
34.6% of the total glucose are in the outer tier
what are more sensitive to dietary carbs
proglycogen
what are synthesized more rapidly following post exercise glycogen depletion reaching a plateau after 24 hours
proglycogen
what builds fast but is smaller
proglycogen
what is slower and more constant
macroglycogen
what synthesis can last for 48 hours post exercise
marcogylcogen
what is responsible for carb loading
macroglycogen
what cannot release glucose
skeletal muscle
what can release glucose
liver
what stores glycogen but in small qyanitities
other cells
what lacks an enzyme to release glucose
muscle
what is the cellular location of glycogen
cytosol
phosphorylate glucose
hexokinase and glucokinase
make UDP glucose
UTP utilization
pyrophosphatase
initiation glycogen synthesis
connect glucose to glcogenin
elongation of the chain in glycogen synthesis
glycogen synthesis adds glucoses
branching in glycogen synthesis
4:6 transfer
what is a protein that starts the glycogen chain with the amino acid tyrosine
glycogenin
what is the initiation enzyme
glycogen initiator synthase
what is 1 ATP broken down to make
glucose 6 phosphate
what it UTP broken down to create
UDP glucose
what is pyrophosphate broken down to create
UDP glucose
what happens when you are resynthesizing glycogen
you are using ATP
what is the equivalence of 3 ATPs broken down
to attach each glucose
glucose synthase has what bonds
a(1-4)
elongation of the chain is done by what enzyme by adding glucose molecules
glycogen synthase
branching occurs by what enzyme
glucosyl 4:6 transferase
glucosyl 4:6 transferase has what bond
a(1-6)
what type of carbon chain are taken from the end and attached to another glucose molecule in the chain
5:8
what kind of bond can glycogen synthase add
a(1-4)
what bond can be added to additional growing chains
a(1-6) by 4:6 transferase
what is the result of adding a(1-4) bonds and a(1-6) bonds
highly branched structure
what are the two main enzymes of regulation
glycogen synthase
glycogen phosphorylase
low atp lots of ADP AMP low glucose glucagon muscle contraction
glycogen phosphosylase
lots of ATP
lots of glucose
insulin
low glycogen levels
glycogen synthase
what is glycogen synthase a key enzyme responsible for
synthesis of glycogen
muscle glycogen concentration is a far more potent regulator of glycogen synthase activity then what
insulin or muscle contraction
what is glycogen synthase bound to a part of
glycogen protein complex
what happens when the concentration of glycogen decreases
glycogen synthase is released
what is the most potent stimulator of glycogen synthase
glycogen levels within the muscle
what does intense exercise burn
muscle and liver glycogen
what does exercise do
Glut 4 translocation
Glut 4 transcription-translation (more transporters)
what happens post exercise
stimulates glycogen synthesis (free glycogen synthase)
increases insulin sensitivity
what type of fiber is responsible for more hypertrophy
TYPE II
what happens after intense exercise
glycogen synthesis has an initial high rate
maximal activity during the first 30 min
rapid decline to about 1/5 by 60 min
reduced by 1/9 by 120min
what are two reasons for the decline after intense exercise
increased glucose uptake (gluts 4)
increased glycogen enzyme activity (glycogen synthase)
the rapid phase is what
insulin independent
occurs when glycogen levels are relatively low and carbs are provided quick after exercise
30-60 min
the slow phase what happens
several hours later
insulin dependent
much slower rate of glycogen synthesis
must had carbs and insulin availible
where is glycogen primarily stored
liver and skeletal muscle
what happens to glycogen synthase after high glycemic carbs are consumed after exercise
the resaultant hyperinsulinemia leads to only a slight increase of glycogen synthase
by adding carbs it will increase insulin but what will it not have an effect on
no additive effect on glycogen synthase
what happens two hours post exercise to the number of glucose transporters associated with the sarcolemma
it returns to the pre exercise concentration
what may be 45% lower when carb ingestion post exercise is delayed by 2 hours compared with immediate consumption post exercsise
muscle glycogen synthesis rates lower
what does consuming carbs after exercise increase
increase glycogen synthesis
what does it meant when you do not consume carbs after exercise but are still able to build glycogen
you are catabolizing amino acids to make glycogen
T/F
CHO supplements provided at 2 hour interval may not adequately increase and maintain blood glucose and insulin levels for 2 hours
true
by ingestion of carbs and proteins after exercise what happens in comparison to just ingesting carbs alone
it leads to a higher muscle glycogen synthesis rate
when intaking a high amount of carbs and some proteins what will happen
it will not lead to a higher glycogen synthesis in comparison with just intaking small amounts of both carbs and proteins together
what different types of proteins impact muscle glycogen levels
(faster to slower)
1) whey protein hydrosylates
2) whey protein
3) casein hydrosylates
4) brain chain amino acids
do trained or untrained have a higher increase in glycogen storage
trained have a 2 fold higher increase
what is the better teh quality of the carb or the quantity of the carb in GI?
the quality is better
the higher the glycemic load the greater the expected elevation in blood glucose and in the insulinogenic effect of food
T/F
T
what is glycemic load
the glycemic index times the grams of carbs in a serving of the food
what is long term consumption of a diet with a relative high glycemic load associated with
associated with an increased risk of type 2 diabetes and coronary heart disease
the longer and higher the elevation of blood glucose the greater the risk for what
developing chronic disease and obesity
what are high GI meals more effective at replenishing muscle glycogen stores during what phase of recovery
the second phase
allows a faster not better repletion
what does low insulin during exercise allow
allows a increased in FFA concentration
blood glucose levels tend to be higher in the later phase of prolonged exercise when subjects are fed what
low GI compared with high GI pre exercise meals
what happens to insulin regardless of what you consume before you exercise
insulin levels decrease and reach the same values regardless of the GI of the pre exercise meal
glucose and glucose/fructose solutions ingested at a rate of 90g/h are equally effective at what
restoring muscle glycogen in exercise muscles during the recovery from exhaustive exercise
why is fructose thought to mediate this effectof very low doses of fructose are added to a glucose containing meal glucose tolerance is improved
activating glucokinase
low dose fructose infusion cause a 3 fold increase in net hepatic glycogen synthesis exclusively through
stimulation of glycogen synthase flux
what has a higher Km which takes more glucose to get it going
glucokinase
what is not inhibited by glucose 6 phosphate which keeps going
glucokinase
what is stimulated by insulin and fructose
glucokinase
what is inhibted by G6P
hexokinase
what do low doses of fructose cause a 3 fold increase in
liver glycogen synthesis
what do small amounts of fructose cause a release of
glucokinase from a regulatory protein
F6P binds to a regulatory protein and inhibits
glucokinase
when F1P binds to a regulatory protein what is set free and activated
glucokinase
what is the main endogenous source of glucose
the liver is the fasted state
following glucose consumption what consumes it
the liver along with removing 1/3 of an oral carb load
what will not cause the liver to take in glucose when blood glucose is in the normal range
insulin
what is the primary site of fructose disposal
the liver is 70% total
what enzymes are essential for fructose metabolism ana are highly expressed in the liver
fructokinase
triokinase (limited expression in muscle and adipose tissue)
why are high levels of fructose not good
liver has high uptake
increased fat lactate and glycerol formation
what are relatively the same
HFCS and sucrose
what has no benefit for muscle glycogen synthesis
fructose
what low doses increase liver glycogen synthesis
fructose
glycogen regulation synthesis
1) high blood glucose
2) insulin
3) fructose
4) low glycogen content
5) high energy charge
6) ATP
glycogen regulation breakdown
1) low blood glucose
2) glucagon
3) low energy charge
4) ADP AMP
5) calcium
