cis- and trans- linkage

[Ivan Brockway]

     I'm a pre-med Bio. major  at Norfolk State University.  My
'Genetics' prof. wants us to find out what we can about cis- and trans-
forms of linkage.  All I've been able to find out in books I've found is
how they relate to regulation of gene metabolism.  Any help would be
appreciated.
     Thank-you.
                          Yours truly,
                           Ivan J. Brockway