Final answer:
In the lytic cycle, step 2 is entry or penetration of the phage DNA into the bacterial cell. In the lysogenic cycle, step 2 involves the integration of phage DNA into the host's genome to form a prophage that is passed to new cells until environmental triggers cause it to enter the lytic cycle.
Step-by-step explanation:
Step 2 in the lytic and lysogenic cycles of a bacteriophage involves different processes. In the lytic cycle, the second step is the entry or penetration of the phage DNA into the host cell. It is facilitated through the contraction of the tail sheath, which acts like a hypodermic needle to inject the viral genome through the cell wall and membrane. The phage DNA then remains independent within the host cell.
In the lysogenic cycle, step 2 involves the integration of phage DNA into the host's genome, forming what is known as a prophage. This prophage is then replicated along with the host's DNA and is passed on to subsequent generations. This lysogenic state can be maintained until environmental stressors such as starvation or exposure to toxic chemicals trigger the excision of the prophage and its entry into the lytic cycle.