Watson and Crick's discovery didn't come out of the blue. As early as 1943 Oswald Avery proved what had been suspected: that DNA, a nucleic acid, carries genetic information. But no one knew how ...

The newly synthesized DNA (light blue) can then be joined with the 5' end of the resected strand, forming a double Holliday junction (double-strand break repair; DSBR), or can be displaced and ...