glycolysis and regulation Flashcards
completely reliant on glycolysis
red blood cells
what cells oxidize glucose to pyruvate to generate ATP
all cells
products of anaerobic glycolysis vs aerobic
lactate as opposed to TCA cycle participation
LDH does what to produce lactate
NADH is oxidized to NAD+ in the cytosol which is used in a step to convert 1-glyceraldehyde-3P to 1,3BPG
how is lactate removed from RBCs and exercising tissue?
Cori Cycle
Cori cycle links
liver and muscle
Describe the Cori Cycle
- in RBC glucose goes through glycolysis to yield 2 lactate
- 2 lactates are transferred to liver through blood
- 2 lactate in liver reconverted to pyruvate by LDH then to glucose by gluconeogenesis
what happens when you produce too much lactate?
lactic acidosis
how do you get lactic acidosis and what are some causes
increased NADH/NAD+ ratio which prevents pyruvate from getting into TCA cycle and directs to lactate.
causes: excess alcohol, hypoxia, and TCA/ETC cycle issues
glycolysis is a major pathway for oxidizing glucose and
metabolizing other dietary sugars, fructose and galactose
ATP/ADP ratio is high are we going through glycolysis?
no
ATP/ADP ration is low but concentration of AMP and ADP are. glycolysis rate will ___
increase
hexokinase inhibited by ___
Glucose 6-phosphate
PFK1 inhibited by ____ and activated by ___
- = ATP and citrate \+ = AMP and F2,6-bisphosphate
pyruvate kinase inhibited by ___ and activated by ____
- = ATP \+ = F1,6-Bisphosphate
Hexokinase vs Glucokinase Km
glucokinase high
hexokinase low
Hexokinase vs Glucokinase affinity for glucose
glucokinase low
hexokinase high
Glucokinase found in ____ while hexokinase found in ____
glucokinase: liver and pancreatic beta cells
hexokinase: all other cells
Hexokinase vs Glucokinase Vmax
glucokinase higher
hexokinase lower
Hexokinase vs Glucokinase induced by insulin?
glucokinase yes
hexokinase no
Hexokinase vs Glucokinase feedback inhibited by glucose-6-P?
glucokinase no
hexokinase yes
PFK1 is a tetramer and has 6 binding sites that are:
2 substrates: ATP and Fructose 6-P
4 allosteric modulators: inhibitors are ATP and citrate while activators are AMP and Fructose 2,6 bisphosphate
what enzyme senses hormonal signaling by insulin and glucagon
PFK1
how is PFK acting in muscle cells during activity?
AMP high, ATP low so glycolysis is promoted
After a meal, insulin is high. what happens with PFK1, FBPase-2, and PFK2?
PFK2 is active generating F2,6BP which activates PFK1. glycolysis is stimulated
In a fasting state. what happens with PFK1, FBPase-2, and PFK2?
FBPase-2 is active causing F2,6BP levels to fall which inactivates PFK1. glycolysis is inhibited
pyruvate kinase allosteric activators and inhibitors
- = ATP \+ = F1,6BP
pyruvate kinase activation by F1,6BP is example of ____
feed forward activation
When glucose is low, glucagon is ___, PKA is (active or inactive), liver PK gets phosphorylated, and is turned off. This is the switch to _____
high. active
gluconeogenesis
reduced pyruvate kinase: glycolysis is inhibited, PEP enters _____
gluconeogenesis
Fate of pyruvate: aerobic, fed conditions:
pyruvate to acetyl CoA or alanine
Fate of pyruvate: anaerobic, fed condition:
pyruvate to lactate
Fate of pyruvate: aerobic, fasting:
pyruvate to oxaloacetate
what inhibits Glyceraldehyde 3-P dehydrogenase?
mercury and arsenate
how does mercury inhibit Glyceraldehyde 3-P dehydrogenase?
inactivates the enzyme
how does arsenate inhibit Glyceraldehyde 3-P dehydrogenase?
substitutes with inorganic P in the reaction and forms 1-arseno-3 phosphoglycerate which is an unstable molecule
Pyruvate kinase adds phosphate to what molecule
ADP
Partial lack of ____ or _____ activity depletes cells of ATP
pyruvate kinase
phosphoglycerate kinase
Cells need ATP to
export electrolytes and to maintain proper osmotic balance between cytosol and extracellular compartment.
No ATP leads to
swelling and destruction of RBCs which leads to hemolytic anemia
Hereditary fructose intolerance is a defect in what enzyme
aldolase B
Hereditary fructose intolerance causes
cellular phosphate to accumulate in Fructose 1-P form which depletes cell of inorganic P. inorganic P becomes too low for glyceraldehyde 3P dehydrogenase to function. ultimately, lack of aldolase B activity prevents liver cell from making ATP
