Our book explains how glucose from the blood plasma gets inside red blood cells via facilitated transport.
It states here in the book that the glucose will be transported inside by a carrier protein. Then the glucose will be phosphorylated by ATP. The phosphorylation of glucose molecules maintains the concentration gradient. This prevents the glucose from diffusing back to the blood plasma.
Based from my current understanding, concentration only change when the number of dissolved molecules changes.
My question is, "How can phosphorylation maintain the concentration gradient if it doesn't change the number of molecules inside the red blood cell?"