Final answer:
Transducing viruses lacking the gag-pol-env genes are unable to replicate and produce new virions because they cannot generate the necessary viral components or enzymes such as reverse transcriptase without help from a host cell.
Step-by-step explanation:
Transducing viruses that lack the normal gag-pol-env genes are unable to replicate and produce infectious virions by themselves. They require the host cell's machinery for successful reproduction.
To clarify, these genes provide the information necessary for producing viral components such as the structural proteins and enzymes like reverse transcriptase. Without these, the virus cannot go through the full lifecycle of infecting a host cell, creating new virions, and subsequently exiting the host cell to infect other cells.
In the case of retroviruses like HIV, reverse transcriptase is crucial for reverse transcription, where the viral RNA is converted into DNA, which is then inserted into the host genome. This step is mandatory for the creation of new viruses. Therefore, without the essential gag-pol-env genes or the ability to supplement the deficient areas, transducing viruses cannot complete the replication cycle independently.