The Cell Membrane Selective Permeability o the cell

The Cell Membrane

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

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

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

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

The Fluid Mosaic Model: o describes the arrangement of molecules that make up the cell membrane o the cell membrane is not rigid but fluid o each layer can move from side to side and slide past each other, as a result, it acts like a fluid o 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: -helps in identifying cell types phospholipid carbohydrate chain protein 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