Final answer:
The first step in the life cycle of non-enveloped DNA animal viruses involves the virus attaching to a host cell and penetrating it. This is achieved through receptor-mediated endocytosis or the formation of channels in the host cell membrane by capsid proteins. Following penetration, the viral DNA is released into the host cell's cytoplasm for replication.
Step-by-step explanation:
Step One of Non-Enveloped DNA Animal Virus Life Cycle: Attachment and Penetration
The initial step in the life cycle of non-enveloped DNA animal viruses is the attachment and penetration of the host cell. Unlike their enveloped counterparts, these viruses do not have a lipid envelope and must employ other mechanisms for entry. One common method is the virus being taken into the host cell via receptor-mediated endocytosis, which involves the binding of a viral capsid protein to a specific receptor on the host cell's surface, triggering internalization of the virus into a vesicle. Alternatively, capsid proteins may undergo conformational changes after receptor binding, creating channels in the host cell membrane, allowing the viral genome to be 'injected' into the host cell.
Once inside the host cell, the viral capsid is typically degraded, and the viral DNA is released into the cell's cytoplasm where it can then proceed to the next stage of the life cycle, which involves replication and synthesis of viral components.