INTRODUCTION TO CELL MEMBRANE     Each cell is defined by a boundary called membrane.             Membrane is a lipid bilayer.  
 
 
  Each lipid molecule has a hydrophilic head(water loving) and hydrobhobic tail(water hating).  
 
 
 
  Of all the existing lipids, phospholipids are present in most abundance. Tails are usually fatty acids and they can differ in length(14-24).       Tail usualy contains atleast one cis double bond to create a kink.         A SIMPLE PICTURE OF MEMBRANE   Phosphorous atoms are shown in green, nitrogen atoms in dark blue, lipid oxygen atoms in red, terminal chain groups in magenta and other carbon atoms in gray :the carbon hydrogen atoms are omitted.  The water molecules are shown in yellow(oxygen) and white (hydrogen).   "Oh! I know all this"  Do you feel so?    LET US GO A LITTLE DEEP ABOUT MEMBRANE