Indicate whether the following statements are true or false. If a statement is f
ID: 164083 • Letter: I
Question
Indicate whether the following statements are true or false. If a statement is false, explain why it is false.
A. The proteins of the electron-transport chain remove a pair of high-energy electrons from the cofactors NADH and FADH2, after which the electrons move across the inner mitochondrial membrane to maintain the voltage gradient.
B. Gluconeogenesis is a linear reaction pathway that the cell employs to generate glucose from pyruvate and is exactly the reverse of the reactions in the glycolytic pathway.
C. With respect to the amount of energy stored in molecules of the body, 6 g of glycogen is the equivalent of 1 g of fat.
D. Glycogen phosphorylase cleaves glucose monomers from the glycogen polymer, phosphorylating it at the same time so that it can be fed unchanged into the glycolytic pathway.
Explanation / Answer
A. The given statement is false. This is because the electrochemical gradient generates proton motive force that move the protons uphill from matrix across inner mitochondrial membrane. The multiprotein complexes in the inner mitochondrial membrane contain prosthetic groups that carry electrons through series of molecules and synthesize ATP.
B. Gluconeogenesis is the synthesis of glucose from non-carbohydrate substances like pyruvate. In gluconeogenesis, pyruvate and ATP are converted to glucose. The end products are glucose, ADP, GDP, Pi and NAD+. This is an anabolic process and appears as reverse of glycolysis except in 1, 3 and 10 reactions that are irreversible. These reactions are catalyzed by different enzymes in gluconeogenesis. The given statement is true.
C. The given statement is true. This is because 1 g of fats provide 9Kcal energy while 1 gram of carbohydrates provide only 4Kcal. Fatty acids are much reduced. Triacylglycerols are nonpolar and stotred in anhydrous from while carbohydrates like glycogenare much more hydrated. About 1 g of dry glycogen can bind to 2 g of water and a gram of nearly anhydrous fat stores more than six times as much energy as a gram of hydrated glycogen.
D. The given statement is false. In glycogenolysis, glycogen is converted to glucose – 1 – phosphate in phosphorolysis reaction of step 1. The step2 is isomerization of glucose – 1 – phosphate into glucose – 6 – phosphate which enters into glycolysis. The reaction is catalyzed by phosphoglucomutase enzyme.