Final answer:
Retroviruses can acquire oncogenes and proto-oncogenes, which are not part of their natural genome, through integration with the host DNA. Tumor suppressor genes are not acquired in this way. Retroviruses, such as HIV, use reverse transcriptase to replicate, and drugs like AZT target this process.Option 3 is the correct answer.
Step-by-step explanation:
Genes that are not part of the retroviral genome, but can be acquired by the virus, include oncogenes and proto-oncogenes. Retroviruses are known for inserting their genome into the host cell DNA. During this process, they can occasionally integrate next to a proto-oncogene, leading to its overexpression and potentially causing cancer. In contrast, tumor suppressor genes are not typically acquired by retroviruses but can be affected by the viral insertion, leading to loss of function and contributing to cancer development. Therefore, oncogenes and proto-oncogenes can be acquired by the virus, while tumor suppressor genes and viral genes are not acquired but are a natural part of the virus's genetic structure.
Retroviruses like HIV use a special enzyme called reverse transcriptase to convert their RNA genome into DNA within the host cell. This allows them to become part of the host cell's genome and is a distinctive feature of how retroviruses replicate. Drugs targeting reverse transcriptase, like AZT, are used to inhibit HIV replication.