Final answer:
Filamentous phages, such as Bacteriophage M13, contain single-stranded DNA. They create a double-stranded DNA intermediate in the host bacterial cell before the original single strand is packaged into new viruses.
Step-by-step explanation:
The filamentous phages all contain single-stranded DNA (ssDNA) as their genetic material. These viruses, like the Bacteriophage M13, inject their DNA into a host bacterial cell through mechanisms like the pilus during processes akin to bacterial conjugation. Once inside the host cell, the phage DNA synthesizes a complementary strand, converting it into a double-stranded intermediate, also referred to as the replicative form (RF). This RF acts similarly to a plasmid within the bacterial cell and can be used in recombinant DNA technology. Additionally, for such viruses, only the (+) strand, which is the original single-stranded DNA, is packaged into new phage particles that are then released to infect other cells.