DNA from Bacteriophage Lambda: Molecular Length and Conformation

The length of the DNA molecules from wild-type lambda bacteriophage is 17.2 micro, corresponding to a molecular weight of 33 million in the B form. The molecules from a double-deletion mutant of lambda are 23 percent shorter. Both types of molecules join ends at 60 degrees C to form circular molecules or polymers. The point of junction cannot be distinguished by any irregularity in the uniform duplex molecule.