KAZAK 2 Flashcards
what is the definition of metabolism
process through which living systems acquire and utilise the free energy they need to carry out their various functions
what is the Pasteur effect
when you expose anaerobic yeast to O2, the rate of glucose usage quickly goes down
what are the relative levels of intermediates after oxygenation of anaerobic yeast?
PFK activity goes down
which means that there is less FBP
any intermediate after that decreases in number
and the intermediates before that accumulate
what are the regulators of rate controlling reactions?
adenylate charge (ATP:ADP ratio)
fuel stores (Cell can sense how much fuel storage it has and adjust accordingly)
what are the three reactions that are heavily rate controlled
glucose to G6P
glycolysis; hexokinase
gluconeogenesis: G6P
F6P to FBP
glycolysis: PFK
gluconeogenesis: FBPase
PEP to pyruvate
glycolysis: pyruvate kinase
gluconeogenesis: pyruvate carboxylase+PEPCK
how is hexokinase regulated?
hexokinase is regulated by product inhibition
G6P will inhibit the enzyme itself
how is PFK regulated?
activated by F2,6BP AMP, ADP
inhibited by ATP and citrate
this makes sure that there are no futile pathways
ATP is both a substrate and an inhibitor
how do the 2 ATP binding sites on PFK work?
active site has a high affinity for ATP
when there’s little ATP it will work
there is also an allosteric site
has a low affinity for ATP
when there is high enough ATP it will bind to that allosteric site and the enzyme will be stopped
how is PFK regulated by F2,6BP?
PFK-2/FBPase-2 has two activities
it generates F26BP from F6P
F26BP will inhibit PFK
PFK-2 converts F6P to F2,6BP
FBPase-2 convertes F2,6BP to F6P
how is pyruvate kinase regulated
inhibited by high adenylate charge (ATP) and high fuel stores (acetyl CoA)
alanine
stop glycolysis: there’s enough things being made
