The Plasma Membrane aka the cell membrane

Cell membrane Facts 1. Serves as "gateway + barrier for cell" 2. Made up of phospholipids and proteins. 3. Separates the contents of the cell from the external environment. 4. It is extremely thin (you could stack 10,000 plasma membranes to equal the thickness of a piece of paper).

The Cell membrane functions to: Control what goes in and out of a cell. Anchors the cytoskeleton to help provide shape. Attaches to a substrate outside of the cell or to other cells to help form tissues Controls the transportation of substances across the membrane by using proteins as carriers and channels Contains receptors that allow cells to communicate through chemical messages Contains recognition proteins which help identify the cell, so the immune system does not attack it.

Phospholipids Has a hydrophilic (water loving head) Hydrophobic (water fearing) Tail Made up mostly of carbon (black)& Hydrogen (light blue)

Phospholipid bi-layer The cell membrane is made up of 2 layers of phospholipids. The Hydrophilic heads face out. The Hydrophobic tails face inward

Other Membrane components Cholesterol makes the cell membrane more stiff and less permeable.

Membrane Proteins function to: Transport proteins – regulate the movement of water-soluble molecules through the cell membrane. Receptor proteins –recognizes and binds to specific molecules. Often trigger some response by the cell such as endocytosis or cell division. recognition proteins – identifies the cell as belonging to a specific species or organ. Helps immune system tell invading cells from cells belonging to the organism.