Question

Phosphorylation of glucose following its transport into a cell

A) targets the glucose for transport back out of the cell.
B) decreases glucose transport into the cell by decreasing its concentration gradient across the plasma membrane.
C) increases glucose transport into the cell by increasing its concentration gradient across the plasma membrane.
D) converts glucose into a form that can more easily be exported from the cell.
E) maintains a higher level of glucose outside the cell.

Answer 1

Phosphorylation of glucose by hexokinase using ATP forms glucose-6-phosphate, which is unable to cross the cell membrane easily. This traps the glucose inside the cell and maintains a lower concentration outside, allowing continuous transport into the cell.

Step-by-step explanation:

Function of Glucose Phosphorylation

The process of glucose phosphorylation within a cell plays a crucial role in the cell's metabolism. When glucose is transported into the cell, the enzyme hexokinase catalyzes the addition of a phosphate group to the glucose molecule using ATP, a reaction that forms glucose-6-phosphate. This reaction is important for two primary reasons. First, the phosphorylation of glucose increases its chemical reactivity, which is necessary for subsequent metabolic reactions. Secondly, phosphorylated glucose cannot easily cross the cell membrane, meaning that phosphorylation essentially traps the glucose within the cell. As a consequence of phosphorylation, glucose is maintained at a lower concentration outside the cell compared to inside, which allows for continued glucose transport into the cell down its concentration gradient.

Given the information and options provided, the correct answer is B: phosphorylation of glucose decreases glucose transport into the cell by decreasing its concentration gradient across the plasma membrane.