Final answer:
A virus can infect animals, plants, or bacteria, whereas a bacteriophage, or phage, specifically infects bacteria. Bacteriophages inject their DNA into the host cell, unlike animal viruses which enter the host cell whole. Bacteriophages can replicate via lytic or lysogenic cycles, with examples including T4 (lytic) and λ (lambda) phage (lysogenic).
Step-by-step explanation:
The primary difference between a virus and a bacteriophage (phage) lies in their hosts and methods of infection. A virus is a broad term that refers to a microscopic infectious agent that can infect various types of living organisms, including animals, plants, and bacteria. In contrast, a bacteriophage is a type of virus that specifically infects bacteria.
Bacteriophages bind to surface receptors on a bacterial cell and inject only their DNA into the host, leaving the protein coat outside. This is in contrast to many animal viruses, which typically enter the host cell in their entirety, either by endocytosis or by membrane fusion. Once inside, a phage can enter either a lytic or lysogenic cycle. The lytic cycle results in the production of new phages and the destruction of the bacterial cell. In contrast, the lysogenic cycle involves the integration of the phage DNA into the host cell's genome, where it can replicate along with the cell's DNA without causing immediate harm. An example of a bacteriophage that uses the lytic cycle is T4, while λ (lambda) phage can undergo a lysogenic cycle.