energy Producers Flashcards
Is glucokinase inhibited by its products?
glucose-6-phosphate does not inhibite glucokinase
what stimulates glucokinase?
insulin and fructose
km of glucokinase?
high km ( it takes more reactant to make it go faster)
Hw is hexokinase inhibited?
inhibition of phosphofructokiase (PFK)
What does heokinase do?
catalyzes the first step in glycolysis
what is the first rate limiting step of glycolysis?
phosphofructokinase (PFK)
What is the first “committed step”?
PFK
What inhibits PFK?
Decresed pH ( a significant drop), Citrate (intermediate of krebs cycle), end products (fructose-1,6-bisphosphate), high energy charge
what kind of enzyme is PFK?`
Allosteric enzyme (ATP binds to the enzyme and decreases its activity)
What does PFK-1 do?
catlyzes the formation of fructose-1,6-bisphosphate
what does PFK-2 do?
catalyzes formation of fructose-2,6-bisphosphate in a different pathway.
what is the most potent activator of PFK-1?
Fructose-2,6-bisphosphate
what stimulatres PFK-2?
insulin
what does PFK-2 stimulate?
glycolysis and PFK in the liver
what inhibits PFK-2?
gluconeogenesis
What does PFK-2 phosphorylate?
fructose-6-phosphate
is pyruvate kinase an irreversible step in glycolysis?
yes, the third irreversible step
what inhibits pyruvate kinase?
alanine
what stimulates pyruvate kinase?
fructose-1,6-bisphostphate
Does glucagon inhibit glycolysis?
yes by decreasing fructose-2,6-bisphosphate
how can we re-activate pyruvate kinase?
by dephosphorylation
How is pyruvate kinase inactivated in the liver?
Glucagon, phosphorylation of Pk
What cant PEP continue in the liver in the presence of glucagon?
glycolysis
when is glucagon secreted?`
when blood glucose is low
primary target of glucagon?
the liver
what is the objective of glucagon?
elevate blood glucose
are there glucagon receptor in muscle?
no
what are the fates of pyruvate?
Alanine, Lactate, Aerobic metabolism
When the energy charge is low, amino acids jump into the Krebds cycle. When they do this, they throw off NH3+. Pyrvate picks up what to turn into Alanine?
NH3+
What does Alanine inhibit?
pyruvate kinase
pyruvate + NADH ->?
Lactate + NAD+
? + ? -> Lactate + NAD+
pyruvate + NADH
what is starch degraded into in the intestines?
glucose
sucrose is made of what?
Glucose + fructose
LActose is composed of what?
Glucose + Galactose
location where glycolysis occurs?
Cytosol
Products of glycolysis?
ATP, NADH, pyruvate and lactic acid, alanine
what does lactate dehydrogenase do?
turns pyruvate into lactate
when is lactic acid produced?
when glycolysis runs fast
when does lactate inhibit glycolysis?
when a large production of lactate occurs by dropping the ph and thus inhibiting PFK.
when there is moderate amount of Lactate, what is produced to stimulate G3P dehydrogenase?
NAD+
in muscle and kidney, fructose is phosphorylated into fructose-6-phosphate by what?
hexokinase
frctuose-6-p from muscle and kidney can enter what cycle?
glycolyses
How many steps does it take to convert Galactose into glucose 6p?
4 steps
What does Galactokinase do?
Converts Galactose (w/ ATP) into Galactose-1-phosphate
What enzyme turns Galactose-1p + UDP glucose into UDP-glactose + Glucose-1p?
transferase
What is the product of this reaction? Galactose-1p + UDP glucose —transferase–> ???
UDP-glucose + glucose-1p
What enzymes turns UDP galactose into UDP glucose?
epimerase
What is the product of this reaction? UDP Galactose —epimerase—> ???
UDP glucose
Glucose-1p is turned into Glucose-6-Phosphate by what enzyme?
Mutase
What are the reactants in Glycolysis?
Glucose, ADP, AMP, NAD+, Pi
What are the key enzymes in glycolysis?
Hexokinase, Phophofructokinase (PFK), pyruvvate kinase
What is glycolysis stimulates by?
Increase in (ADP, AMP, Pi or inorganic phosphate, Ammonia/NH3+), Insulin ad Fructose-2,6-bisphosphate
Glycolysis is inhibited by what?
Increase in ATP ad Citrate, Glucagon and a decrease in pH
