5 Greatest Scientific Discoveries of 20th Century?
                  These are my opinion... What's your opinion.
                  Do you have any related to Cell & Molecular Biology?

1.   Theory of Relativity – Albert Einstein 1905
             if speed of light is a constant , then time & motion are relative to the observer, 
             and mass and energy are equivalent E = mc2   
2.   Atomic Structure & Fission 1911-1938 
              1911 Rutherford discovers atomic particles; 
             1938 Otto Hahn & Fritz Strassman split nucleus of atom releasing energy [fission]
3.   Structure of DNA: J.D. Watson & Francis Crick  1953 
             double helical polynucleotide of ATGC
4.   Greenhouse Effect – Global Warming   1970  
                        awakens us to science of environmental preservation - NOVA site 
5.   Comet Shoemaker-Levy* hits Jupiter   1994  
              ►    March 1993 Gene & Carolyn Shoemaker discover comet – 
                     collides with Jupiter...  offers a suggestion on how LIFE might have begun 
                                                   via organic molecule seeding and water dumping by comets