Back to West Side Story... MAD did indeed do a parody on it. I can only remember a few lines sung to the tune "Maria" titled "Amoeba"
Amoeba...I just met a blob named Amoeba,
----
Chorus: Amoeba..how your two cells do split into four cells.
       And those four cells will split into more cells.
       Amoeba,...I just met a blob named Amoeba.
On a side note, Mad did a version sung to the tune of Bridge over the River Kwai called Comet.
   Comet..It makes your mouth turn green. Comet..It tastes like   
    kerosene. Comet, It makes you vomit...so eat some Comet, and
      vomit, today.