Lecture 16 - regulating glycolysis

Question 1

which 3 reactions in glycolysis are irreversible and why

Answer 1

glucose to G6P
F6P to F1,6BP
phosphoenolpyruvate to pyruvate

cuz large free energy change

Question 2

what regulates glucose to G6P

Answer 2

G6P
acts as inhibitor for hexokinase

Question 3

what regulates phosphofructokinase

Answer 3

AMP (and fructose 2,6 bisP in the liver) upregulates
ATP (and citrate in liver) inhibits
(both allosteric inhibitors)

Question 4

what is special about 3rd step of glycolysis

Answer 4

F6P to F1,6bisP
rate limiting step in glycolysis

Question 5

what 2 enzymes are used to control F6P to F1,6bisP

Answer 5

PFK-1
PFK-2 in the liver

Question 6

how does H+ conc act as a regulator for PFK-1

Answer 6

anarobic resp –> lactic acid = pH falls, H+ rise
inhibits PFK-1 to inhibit glycolysis
to prevent lactic acid accumulatio

Question 7

what regulates PEP to pyruvate

Answer 7

ATP will inhibit pyruvate kinase
F1,6bisP will feed forward activate pyruvate kinase

Question 8

how does ATP inhibit pyruvate kinase

Answer 8

activates protein kinase A
which phosphorylates Ser12 on pyruvate kinase
making it LESS active

Question 9

what will cause pyruvate kinase to be more active

Answer 9

phosphoprotein phosphatase
will desphosph it making it more active