Regulation of Glycolysis and Gluconeogenesis

Question 1

What is futile cycling?

Answer 1

running both pathways that serve opposing roles causing a net loss of energy

Question 2

What is reciprocal control?

Answer 2

the same molecule regulates two enzymes in opposite pathways

Question 3

Which steps in glycolysis and gluconeogenesis are regulated for reciprocal control? How are they regulated?

Answer 3

the two irreversible steps
glycolysis = phosphofructokinase (PFK)
gluconeogenesis = fructose-1,6-bisphosphate (F-1,6-BPase)
allosteric regulation

Question 4

What is the main metabolic intermediate that exerts reciprocal control on PFK and F-1,6-BPase? Which enzyme does it stimulate and which enzyme does it inhibit?

Answer 4

fructose-2,6-bisphosphate (F-2,6-BP)
stimulates PFK thus stimulating glycolysis
inhibits F-1,6-BPase thus inhibiting gluconeogenesis

Question 5

What two hormones help control the intracellular concentration of F-2,6-BP?

Answer 5

insulin = stimulates
glucagon = inhibits