Cell Membrane What is it made of? How does it work?

Cell Membrane Cell membrane is made up of two parts –It is made up of lipids (fat molecules) and proteins. Phospholipid part (75-95%) Protein part(5-25%)

Protein Part of Cell provides  Communication  I.D. tags  Anchors  Gates to exchange large molecules  Pumps

Cell membrane proteins –Channel proteins- allow molecules or ions to enter cell –Receptor proteins-relay information from outside the cell to inside the cell –Marker proteins-act as the name tags of the cell

Questions? What type of proteins would you expect to be present in the following cells? Red blood cell Brain cell Kidney cell Tongue cell Marker proteins because of the blood group antigens Receptor proteins for transferring information Channel proteins to help filter out wastes Receptor proteins for detecting food molecules

Cell Membrane is –Known as the Fluid Mosiac Model  All of the molecules “float” around, exchanging positions  Membrane has flexibility  Tiny spaces between membrane molecules allow certain materials to enter or leave the cell 

 The membrane is "selectively permeable", meaning it selects what substances enter or leave.  In other words, not all substances are allowed to pass through the membrane.

Transportation of Molecules Passive Transport -no energy required -Molecules move high to low conc. 1. Diffusion 2. Facilitated Diffusion 3. Osmosis a. Hypoonic b. Hypertonic c. isotonic Active Transport -needs ENERGY -Molecules move low to high conc. A. Endocytosis 1. Pinocytosis 2. Phagocytosis B. Exocytosis

Diffusion Molecules moving from an area of high concentration to an area of low concentration –Random motion drives diffusion –Movement is based on kinetic energy (speed), charge, and mass of molecules –Equilibrium is reached when there is an even distribution of solute molecules Review: -Solute is the substance being dissolved (example salt) -Solvent is the substance doing the dissolving (example water) (water)

Osmosis: The net movement of water molecules along a concentration gradient from an area of high water concentration to an area of low water concentration through a selectively permeable membrane.