Cell Membrane and TransportCell Membrane and Transport The cell membrane is responsible for moving materials into and out of the cell. There are two types of transport that can occur across the membrane: passive transport and active transport. Passive transport does not require energy and includes the processes of osmosis, diffusion and facilitated diffusion. The graphic shows the phospholipid bilayer and embedded proteins, the two main components of the cell membrane. Phospholipids are made of hydrophilic (water-loving) heads and hydrophobic (water-hating) tails. The phospholipids are arranged opposite to each other, with the heads pointing toward the cell’s environment and the tails aligning to each other. Some small molecules, like oxygen, can move right across the phospholipid bilayerthrough a process called diffusion. Diffusion occurs when molecules move from an area of high concentration to an area of low concentration.