Final answer:
Reverse transcriptase is an enzyme isolated from retroviruses such as HIV and is used to convert single-stranded RNA into double-stranded DNA. It's also a vital tool in genetic engineering and a target for antiviral drugs.
Step-by-step explanation:
The enzyme reverse transcriptase was isolated from retroviruses, which are a group of viruses that have an RNA genome. This enzyme is known for its unique function of converting single-stranded RNA into double-stranded DNA, a process that is crucial for the replication of retroviruses such as HIV. The reverse transcriptase is a key target for antiviral drugs, as it is not found in uninfected host cells and its inhibition does not affect the host's metabolism. It has also become an invaluable tool in genetic engineering and molecular biology, enabling the production of cDNA from mRNA sequences in the laboratory setting. The understanding and utilization of reverse transcriptase have led to advancements in medical research, including the development of reverse transcriptase inhibitors and techniques like reverse transcription PCR (RT-PCR).