QuestionSBA
QuestionChoice
Hexokinase hydrolyses ATP to release a phosphate molecule which is used to generate glucose-6-phosphate from glucose. Hexokinase will not, however, catalyse the opposite reaction, instead requiring glucose-6-phosphatase to hydrolyse phosphate from glucose-6-phosphate during gluconeogenesis.
10001087
b
Hexokinase
QuestionChoice
Fructose-2,6-bisphosphatase catalyses the removal of phosphate from the '2' group of fructose-2,6-bisphosphate. Fructose-2,6-bisphosphate is the most potent known activator of phosphofructokinase-1, stimulating increased glycolysis. Fructose-2,6-bisphosphatase, therefore, down-regulates glycolysis and could be used to indirectly up-regulate gluconeogenesis. However, fructose-2,6-bisphosphatase is not involved in the core processes in the way enzymes like fructose-1,6-bisphosphatase are.

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10001090
e
Fructose-2,6-bisphosphatase
QuestionChoice
Phosphofructokinase-1 catalyses the addition of an extra phosphate group to the '1' position of fructose-6-phosphate to generate fructose-1,6-bisphosphate. Phosphofructokinase-1 will not, however, catalyse the opposite reaction, instead requiring fructose-1,6-bisphosphatase to hydrolyse phosphate from fructose-1,6-bisphosphate during gluconeogenesis.
10001088
c
Phosphofructokinase-1
QuestionChoice
Pyruvate carboxylase hydrolyses ATP to release energy so that it can add a bicarbonate group to pyruvate, generating oxaloacetate. Phosphoenolpyruvate carboxykinase can then use the energy from GTP hydrolysis to remove CO2 from oxaloacetate and generate phosphoenolpyruvate. This overcomes the non-reversible reaction by pyruvate kinase during glycolysis and facilitates gluconeogenesis.
10001086
a
Pyruvate carboxylase
QuestionChoice
Pyruvate kinase catalyses the transfer of a phosphate group from phosphoenolpyruvate to ADP during glycolysis, generating ATP and pyruvate. This reaction, however, has a large Gibbs free energy change and the hydrolysis of a single ATP molecule is insufficient to reverse it. This makes the reaction effectively irreversible. To overcome this during gluconeogenesis, an intermediate step is performed in which an ATP molecule is hydrolysed to produce oxaloacetate. A GTP molecule is then hydrolysed to convert the oxaloacetate into phosphoenolpyruvate oxaloacetate.
10001089
d
Pyruvate kinase
Concept
Chapter
2693
3881
Carbohydrate chemistry
Topic
180
Biochemistry
12764
Which of the following enzymes is directly utilised in the conversion of pyruvate to glucose during gluconeogenesis?
a