BIOCHEMISTRY, BIOMEDICINE & PHARMACEUTICS

                                      MCQ on Glycolysis & Gluconeogenesis 1) Which of the following enzyme is not involved in galactose metabolism? a) Glucokinase b) Galactokinase c) Galactose-1-Phosphate Uridyl transferase d) UDP-Galactose 4- epimerase 2) Which of the following enzyme is defective in galactosemia (type I) - a fatal genetic disorder in infants? a) Glucokinase b) Galactokinase c) Galactose-1-Phosphate Uridyl transferase d) UDP-Galactose 4- epimerase 3) In the liver, the accumulation of which of the following metabolite attenuates the inhibitory of ATP on phosphofructokinase? a) Glucose-6-Phosphate b) Citrate c) Fructose-1,6-Bisphosphate d) Fructose-2,6-Bisphosphate 4) Mutation in which of the following enzymes leads to a glycogen storage disease known as "Tarui’s disease"? a) Glucokinase b) Phosphofructokinase c) Phosphoglucomutase d) Pyruvate Kinase 5) E...

Similar to most metabolic pathways, glucose synthesis and breakdown is regulated by three different mechanisms : a) Allosteric regulators b) Covalent modification c) Changes in gene expression Regulation of glycolytic pathway: As described on the previous page and in figure 1, glycolysis is regulated by three irreversible enzymes namely : Hexokinase / glucokinase, Phosphofructokinase, and Pyruvate kinase. Figure 1: Allosteric Regulators of Glycolysis and Gluconeogenesis  Hexokinase / glucokinase: Hexokinase is a ubiquitously expressed enzyme that sets the pace of glycolysis. Hexokinase has a high affinity for glucose and transfers a negatively charged phosphate group to a glucose molecule. This step traps the glucose inside the cells and funnels it into various metabolic pathways. The high concentration of glucose-6-phosphate signals that the cell no longer requires energy or other biosynthetic pathways, and inhibits enzyme hexokinase. Glucokinase is expres...