Final answer:
The phosphorylation of glucose to form G6P in glycolysis is an exergonic and irreversible reaction, which uses ATP, releases energy, and traps glucose within the cell for further metabolism. The correct options are A and D.
Step-by-step explanation:
The reaction of glucose to form glucose-6-phosphate (G6P) in glycolysis involves ATP and is an important step in cellular respiration. The reaction is catalyzed by the enzyme hexokinase, which transfers a phosphate group from ATP to glucose, forming G6P.
This reaction serves multiple functions, such as trapping the glucose within the cell and making it a more reactive molecule for further metabolism in glycolysis. According to the information given, the overall reaction is exergonic; the free energy change for the reaction is -4 Kcal per mole of G-6-P synthesized, meaning it releases energy. Moreover, the reaction is also considered biologically irreversible, indicating it predominantly proceeds in one direction under physiological conditions.
Energy Dynamics in Glycolysis
During the first half of glycolysis, energy is required, which is provided by the hydrolysis of ATP. This step is both endergonic (requiring energy input) and coupled to the exergonic reaction of ATP hydrolysis. Therefore, the formation of G6P is an energy-requiring step linked to the energy-releasing step of ATP breakdown. This coupling is a common strategy in metabolism, where the energy from favorable reactions is used to drive unfavorable ones.