Final answer:
Animal viruses and bacteriophages can both use lytic and lysogenic lifestyles. Bacteriophages have complex tail structures for DNA injection and often target specific receptors on bacteria, whereas animal viruses may enter host cells entirely and display tropisms for different tissues. Both can lead to productive or latent infections in their respective host cell types.
Step-by-step explanation:
The primary difference between animal viruses and bacteriophages lies in the manner in which they infect and replicate within their host cells. Contrary to the statement that bacteriophages follow only a lytic lifestyle, both animal viruses and bacteriophages can engage in both lytic and lysogenic lifestyles. In the lytic cycle, the virus replicates inside the host cell and then causes the cell to lyse, releasing new viral particles. The lysogenic cycle involves the integration of the viral genome into the host cell's genome, where it can remain dormant until triggered to enter the lytic cycle.
Animal viruses often employ additional mechanisms like endocytosis or membrane fusion to enter host cells. Moreover, animal viruses can also enter a state of latency, where the virus remains in the host cell without active replication, a condition somewhat akin to the lysogenic state in bacteriophages, although the terms lysogenic and latency are not interchangeable. In terms of structural differences, bacteriophages often have complex tail structures to inject their genetic material into bacterial cells, while animal viruses may completely enter the host cells. These differences are crucial to understanding the diverse nature of viral infections and their interactions with host organisms.