The linear dsDNA genomes encode from 27 to over 600 genes that are highly clustered
according to function and tend to be arranged in large operons. Complete functional
genomic maps are very diverse and available for only a relatively small number of tailed
viruses. Virion DNAs may be circularly permuted and/or terminally redundant, have
single-stranded gaps, or have covalently-bound terminal proteins. The ends of these linear
molecules can be blunt or have complementary protruding 5'- or 3'-ends (the “cohesive” or
“sticky” ends, which can base pair to circularize the molecule). Prophages of temperate
tailed viruses are either integrated into the host genome or replicate as circular or linear
plasmids; these linear plasmids have covalently-closed hairpin telomeres.