The+Plasma+Membrane

=Plasma Membrane= The Plasma Membrane is the membrane at the boundary of every cell that acts as a selective barrier, thereby regulating the cells chemical composition. It is included in all cells, both prokaryotic & eukaryotic. The Plasma Membrane encloses their contents and serves as a barrier to the outside environment. The membrane is used as a boundary, holding the cell contents together and keeping substances out of the interior of the cell. The plasma membrane is permeable to specific molecules, but allows nutrients and essentials to enter the cell and waste out of it. Oxygen, carbon dioxide, and water are the small molecules that are able to pass freely across the membrane, but the larger molecules, like amino acids and sugars are carefully regulated.

The plasma membrane is made from two layers of phospholipids (fats), this is known as the bilayer. The phospholipids form a top and bottom layer all by it's self and the tails of the fats form together. Inside the phospholipids in the membrane, a lot of proteins have made it their home. Phospholipids are characteristically hydrophilic (meaning water loving) and their lipid tail regions are hydrophobic. Within the phospholipid bilayer of the plasma membrane many different proteins are included, while other proteins simply attached to the surfaces of the bilayer.Some of those proteins, mostly those that are at least exposed on the surfaces tend to have carbohydrates attached to their outer surfaces and are referred to as glycoproteins. The positioning of proteins along the plasma membrane related to parts of a group of the filaments that comprise the cytoskeleton, which helps keep them in place.

The Phosphate from the Plasma Membrane may have other polar groups such as choline, enthanolamine, serine, inositol which increases hydrophilicity. Cholesterol can make up to 50% of animal plasma membrane

http://micro.magnet.fsu.edu/cells/plasmamembrane/plasmamembrane.html http://www.uic.edu/classes/bios/bios100/lecturesf04am/lect08.htm
 * References:**


 * Alicia and Salesha**