How do neutral solutes move across the plasma membrane? Can the polar molecules also move across it in the same way? If not, then how are these transported across the membrane?
Explanation The plasma membrane is the outer covering of the cell surface present within the cell wall. The plasma membrane regulates the movement of molecules and solutes into the cell. The plasma membrane consists of a lipid bilayer. This lipid bilayer is semi-permeable and consists of hydrophobic residues in it. The neutral solute travels through the plasma membrane by the process of simple diffusion. It is the movement of solute from the region of higher to lower concentration until the equilibrium is achieved. Polar solutes are positively charged. The plasma contains the lipid bilayer, and it is hydrophobic. This hydrophobic nature repels the polar molecule. The polar molecule cannot pass through the plasma membrane easily. Hence the transportation of the polar solutes does not take place through the process of simple diffusion. Polar solutes transport across the plasma membrane through the process of facilitated diffusion. Facilitated diffusion is defined as the transportation of the polar substance-using transport proteins in the plasma membrane. The channel protein and carrier proteins are some examples of the transport protein. This facilitates the movement of the particles through the process of facilitated diffusion. Final Answer Plasma membrane covering the cell surface consists of hydrophobic residues. The semi-permeable nature of the plasma membrane allows the movement of the neutral solutes through it. Since the neutral solute does not contain any charges, it passes through the plasma membrane by the process of diffusion. The positively charged polar solutes do not pass through the plasma membrane directly. The passage of the polar solutes does not take place through the process of simple diffusion. The lipid bilayer in the plasma membrane rejects the polar solutes. Polar solutes are transported through facilitated diffusion. It is the process of transportation of polar molecules with the help of transport proteins. These transport proteins act as the carrier molecule and transport the polar solutes.
