AP BIOLOGY

Detailed explanation-1: -What Do Membranes Do? Cell membranes serve as barriers and gatekeepers. They are semi-permeable, which means that some molecules can diffuse across the lipid bilayer but others cannot.

Detailed explanation-2: -The cell membrane, also called the plasma membrane, is found in all cells and separates the interior of the cell from the outside environment. The cell membrane consists of a lipid bilayer that is semipermeable. The cell membrane regulates the transport of materials entering and exiting the cell.

Detailed explanation-3: -The proteins that sit on the outside of the cell membranes act as the gates. If the same type of molecule needs to leave a cell the gate will open and allow the molecule to leave. Molecules will enter and leave a cell based upon the concentration of that molecule inside of the cell.

Detailed explanation-4: -Aquaporins, also called water channels, are channel proteins from a larger family of major intrinsic proteins that form pores in the membrane of biological cells, mainly facilitating transport of water between cells.

Detailed explanation-5: -The plasma membrane is the outer lining of the cell. It separates the cell from its environment and allows materials to enter and leave the cell.