For simplicity one can think of the + class as having one extra base at some point or other in the genetic message and the - class as having one too few.
-- Francis Crick
   
Francis Crick   Name:
Francis Crick
Type:
Scientist
Nationality:
English
Birth:
June 8, 1916
Death:
July 28, 2004
https://www.nutquote.com/quote/Francis_Crick