The Cell Membrane

Selective Permeability: the cell membrane is said to be semi-permeable or selectively permeable which means it allows some substances to pass but not others

Cell Membrane: forms a boundary between the cell and the outside environment it controls the passage of materials into and out of the cell it consists of a double layer of phospholipids a phospholipid is a lipid made of a phosphate, glycerol, and 2 fatty acid chains phosphate

a phospholipid has a polar “head” and 2 nonpolar “tails” phosphate a phospholipid has a polar “head” and 2 nonpolar “tails” these phospholipids are arranged in a double layer called a lipid bilayer the polar heads form the outer surfaces of the membrane, whereas, the nonpolar tails make up the interior of the lipid bilayer

Lipid Bilayer: Glycerol Hydrophilic Outside of cell = Hydrophobic Inside of cell =

The Fluid Mosaic Model: describes the arrangement of molecules that make up the cell membrane the cell membrane is not rigid but fluid each layer can move from side to side and slide past each other, as a result, it acts like a fluid the cell membrane also has a variety molecules embedded in it which resembles a mosaic made up of different tiles and textures

The Cell Membrane: carbohydrate chain phospholipid protein cholesterol -helps in identifying cell types protein phospholipid carbohydrate chain cholesterol -helps move substances across the cell membrane -strengthens cell membrane

Different Types of Cell Membrane Proteins: 1. transport proteins – helps move substances into and out of a cell 2. marker proteins – identifies cell type 3. receptor proteins – bind to specific substances 4. enzymes – assists in chemical reaction within the cell