CELL MEMBRANE PLASMA MEMBRANE FUNCTIONS Boundary Holds cytoplasm

CELL MEMBRANE

PLASMA MEMBRANE FUNCTIONS • Boundary • Holds cytoplasm in • Protection • Communication: cell to cell

PERMEABILITY • Semi-permeable: regulates what enters and leaves based on size alone (some synthetic membranes) • Selectively or differentially permeable: based on chemical and physical properties = cell membrane

FLUID MOSAIC MODEL

FLUID MOSAIC MODEL

COMPONENTS OF PLASMA MEMBRANE • Phospholipids: phosphate head, fatty acid tails, fluid like consistency • Draw it! • Proteins: embedded to form a mosaic pattern • Peripheral proteins: on inner or outer surface • May be attached to cytoskeleton or to integral proteins • Integral proteins: within the bilayer, hydrophobic and hydrophilic regions, most extend through the bilayer

FUNCTIONS OF INTEGRAL PROTEINS • Channel proteins • Specific carrier proteins • Specific receptor proteins • Cell recognition glycoproteins • Enzymatic proteins

FUNCTIONS OF PROTEINS IN CELL MEMBRANE

CHOLESTEROL • A type of ? • Function: prevents solidification of cell membranes at low temperatures and reduces fluidity at high temperatures.

GLYCOPROTEINS/ GLYCOLIPIDS • Recall…glycogen: a carbohydrate polymer used for energy storage in animals • Glycoproteins are proteins with short chains of sugars attached. • Glycolipids are lipids with short chains of sugars attached Function: Cell recognition and communication

WHY “FLUID MOSAIC MODEL? ”