16 Flashcards
review the steps of glycolysis
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review gibbs free energy
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what three reactions have large change in free energy? in glycolysis
glucose + atp -> glucose + adp
fructose + atp -> fructose + adp
phosphoenolpyruvate + adp -> pyruvate + atp
three big reactions of glycolysis are _____ and their enzymes are _____
irreversible
regulated
change in free energy for all other steps of glycolysis other than the three major ones are close to ____ and these reactions are largely _____
zero
reversible
glycolytic pathway resembles a series of _____ connected by __
resevoirs (metabolic pool)
dams
the irreversible ‘dams’ are irreversible ________ and are _______ of the pathway which _______ glycolysis
reactions
points of regulation
control
______ is the main regulatory enzyme in glycolysis
phosphofructokinase (1 and 2)
allosteric regulation
common mechanism
upstream or downstream metabolites from same or different pathway
general metabolic indicators
allosteric - another side
hexokinase is inhibited by ___
its own product
product inhibition is a form of ____
feedback inhibition
phosphofructokinase 1 and 2 is an ____
allosteric enzyme - regulated by allosteric effectors
when citrate accumulates, there is no need to produce further ____
ATP
ATP build up indicates no need for more ____ - therefore there is PFK-1 ____-
energy
inhibition
sufficient ATP levels mean glycolysis is ____
deactivated
sufficient ATP levels mean glycolysis is ____
deactivated
Low ATP/AMP ratio indicates energy is ______ - therefore PFK-1 _______
needed
activation
when ATP is needed, glycolysis is _____
stimulated
high levels of citrate are _____ of PFK-1: biosyntehtic precursors are ____ and therefore further consumption of ___ is not needed
inhibitory
abundant
glucose
______ is the most important activator for PFK-1 in eukaryotes, controls glycolysis in liver
fructose-2,6-bisphosphate
High H+ concentration also ____ PFK-1: pH falls when muscles work ____, and therefore glycolysis ______ prevents accumulation of lactic acid
Inhibits
Anaerobicaly
Inhibition
When pyruvate and ATP get produced, which acts as an inhibitor?
ATP
Can enzymes change their activity if they are phosphorylated or not?
yes
Which is form of pyruvate kinase is more active? Phosphorylated, or dephosphorylated?
Dephosphorylated
Under aerobic conditions, what happens to pyruvate?
Oxidized to acetyl CoA - citric acid cycle, electron transport chain
Under anaerobic conditions, what happens to pyruvate? (2)
Converted to ethanol (microorganisms, fermentation)
Converted to lactate (muscles, RBC)
Pyruvate decarboxylation involves what important reaction?
Pyruvate dehydrogenase
The pyruvate dehydrogenase complex is a large molecule with ____ enzymes
Three
How many copies of E1, E2, and E3 are there in pyruvate decarboxylation?
24, 24, 12 respectively (60 total subunits)
In eukaryotes, pyruvate dehydrogenase complex is located in the _____
Mitochondrial matrix
In eukaryotes, pyruvate translocase is located in the ____
Inner mitochondrial membrane
Molecules that transport in the same direction are called
Symporter
