Midterm 2 Flashcards
Describe PFK2 and F26BP in the liver compared to the muscle?
PFK2 is phosphorylated by protein kinase a in the liver, PFK2 is inhibited and F26BP is activated. F26BP [ ] is lower and glycolysis is inhibited
PFK2 is phosphorylated by protein kinase a in the muscle, PFK2 is activated and F26Bp is inhibited. F26BP [ ] is higher and glycolysis in activated.
organisms maintain homeostasis by keeping concentrations of metabolites at a _________ state
steady
at steady state rate of synthesis ____ rate of breakdown of metabolites
equals
ATP inhibits the _____ step of glycolysis which is?
commitment step which means with abundant ATP PFK 1 is turned off
rates of biochemical reactions depend on?
- Temperature
- Concentration of reactants vs Products
- Concentrations of effectors
- Activity of the catalyst/enzyme
*describe how the rate of enzyme reaction depends on the concentration of substances?
the rate of enzyme activity is more sensitive to concentraion at low concentrations while the rate becomes insensitive at high substrate concentrations because an enzyme can only bind to one substrate
what is the function of PP2A?
dephosphorylates a number of proteins
phosphorylation is catalyzed by?
protein kinases
dephosphorylation is catalyzed by?
protein phosphatases
typically proteins are phosphorylated on the hydroxyl groups ____ ______ _____
ser thr tyr
increases hexokinase activity enables activation of ___________
glucose
increased PFK 1 activity enables catabolism of activated _______ via _______
glucose via glycolysis
insulin effect on ________ and ________ are major flux controllers
GLUT4 and hexokinase
*HK1 is expressed in ________
all tissues
*HKIV is expressed in the _____
liver
what are isozymes?
different enzymes that catalyze the same reaction
HK4 is regulated by ?
sequestration and transcription
what is favored is AMP is high, low ATP?
Glycolysis
what is favored if AMP is low?
glucogenesis
*what is the function of F26BP?
- regulator
- activates PFK (glycolysis)
- inhibits F16BP (glucogenesis)
*F26BP is produced from _______
F6P
Describe regulation of PFK?
- acitvated by F16BP
- inhibited by ATP, Acetyl COA, alanine
- in the liver inactivated by phosphorylation in response to glucose depletion
what are the two alternative fates for pyruvate?
- store energy as glycogen, generate NADPH via pentose phosphate pathway
- source of acetyl coA, store energy as body fat, make ATP via citric acid cycle
ChREBP activates transcription in response to __________
glucose
FOXO1 activates transcription in response to __________
insulin
glucose residues are removed from glycogen by _______ ______
glycogen phosphorylase
glucose - P must eb isomerized to glucose 6 P to be metabolized, this is done by _____________
phosphoglucomutase
glucose 6P is dephosphoylated in the _______ for transport into the bloodstream, this is preformed by ______________
liver, glucose 6 phosphatase (gluconeogenic enzyme)
glycogen synthesis occurs in the _____ and _______
liver and msucle
what are the 4 enzyme reactions involved in glycogen synthesis?
- UDP glucose pyrophosphorylase
- Glycogen synthase
- Glycogen branching enzyme
- Glycogenin
glycogen storage disease is ?
genetic enzyme deficiencies associated with excessive glycogen accumulation within cells
liver phosphorylase b is not activated by _____
AMP
liver phosphorylase a is deactivated by _________
glucose
do muscle cells contain glucose 6 phosphatase?
no
insulin does what 3 main things?
- increases glucose import into the muscle
- stimulates activity of muscle hexokinase
- activates glycogen synthase
