Final answer:
Glucose entering cells is phosphorylated to glucose-6-phosphate, which can be metabolized for energy in glycolysis. This step is catalyzed by the enzyme hexokinase and requires ATP.
Step-by-step explanation:
Glucose entering cells is phosphorylated to glucose-6-phosphate, which can be metabolized for energy in glycolysis. This phosphorylation step is catalyzed by the enzyme hexokinase, which transfers a phosphate group from ATP to glucose, forming glucose-6-phosphate and ADP. Once glucose is phosphorylated, it can either be stored as glycogen or used as a substrate for glycolysis to produce ATP.