And so what that means is, even if we have a concentration gradient that exists across the cell membrane, because the membrane is predominantly nonpolar hydrophobic, these polar glucose molecules and sugar molecules cannot make their way across the cell membrane. And so the cells create these transmembrane proteins that contain twelve transmembrane alpha helices that we call glucose transporters. And these allow the movement, allow the shuttling of these glucose molecules across the cell membrane. So essentially, upon the binding of the glucose molecule or other monosaccharide onto the glucose transporter, a conformational change takes place that allows the movement of that glucose or other monosaccharide into the cytoplasm of that cell. So let's suppose we have a high concentration of glucose in the blood plasma, a low amount in the inside the cell. And so the glucose will move down into concentration gradient from the outside to the inside.