11.1 Introduction Type of Unit Genome Structure Mode of propagation Consequences Lytic phage dsor ss-DN A or RNA Infects susceptible host Usually kills host linear or circular Lysogenic phage ds-DNA Linear sequence in Im munity to infection host chromosome Plasmid ds-DNA cirde Replicates at defined Im munity to plasmids May be transmissible In same group Episome ds-DNA circle Free circle or linear integrated Ma ay transfer host dna Figure 11.2 Several types of independent genetic units exist in bacteria 消当Figure 11.2 Several types of independent genetic units exist in bacteria. 11.1 Introduction