The Structure And Function Of The Cell Membrane

2.1 describe the structure and function of the cell membrane.

The cell membrane, also known as the plasma membrane, regulates what enters and leaves the cell. The cell membrane also deals with recognition of proteins and transport that regulates the movement of water and soluble molecules throughout the membrane. The cell membrane is composed of phospholipid molecules and consists of two lipid layers in which protein molecules float; this is sometimes referred to as a “lipid sandwich” this surrounds the cell. Like other lipids these are hydrophobic. Diffusion, facilitated diffusion and osmosis are ways in which molecules can travel through the membrane as they’re all passive processes where substances move down a concentration gradient. When the cell needs to move a chemical against a concentrated gradient which is known as active transport.

2.2 Explain the differences between osmosis, diffusion, active transport and bulk transport.

Osmosis occurs in places like the cells of the small intestine and the kidney. Whereas diffusion is the spreading and mixing of the irons or atoms, or any molecules that make up a substance where they are of a higher concentration to a region with a lower concentration. The higher the difference in concentration the faster the rate of diffusion. Similarly facilitated diffusion is a movement of molecules and diffusion across the cell membrane with help from the proteins within the membrane. Facilitated diffusion also increases the rate of particles that cross the cell membrane. These processes do not need any energy to be used by the cell. All three processes are known as passive transport. However, the process where the cell uses energy to move molecules across the membrane is known as active