====== DNA REPLICATION  ======

        * replication origin 
        * replication bubbles
        * replication fork 
        * synthesis of DNA 
          * Only from 5' - 3' end so 
            * for first strand synthesis occurs from top to bottom 
              * it is called as leading strand 
            * for second or antisense strand it occurs from bottom(5'end ) to top (3' end )
              * it is called lagging strand