The question "In which virus is DNA absent?" requires us to identify viruses that do not contain deoxyribonucleic acid (DNA) as their genetic material. Instead, these viruses utilize ribonucleic acid (RNA) for genetic information.
Viruses and their Genetic Material
Viruses are essentially genetic material enclosed in a protein coat. The genetic material can either be DNA or RNA, but not both. This distinction is crucial in understanding viral replication and classification. While many viruses contain DNA, some utilize RNA instead.
RNA Viruses - The Absence of DNA
Viruses that do not contain DNA are known as RNA viruses. These viruses carry their genetic information in the form of RNA. Examples of RNA viruses are:
- Retroviruses: Like HIV (Human Immunodeficiency Virus), these viruses use an enzyme called reverse transcriptase to convert their RNA into DNA, which then integrates into the host cell's genome.
- Influenza viruses: These are responsible for seasonal flu.
- Polioviruses: Cause polio.
- Ebola virus: Causes the deadly Ebola hemorrhagic fever.
- Rhinoviruses: Common cold viruses.
Bacteriophages and Their DNA Content
According to the provided reference, Bacteriophage.09-Jan-2020, Bacteriophages are viruses that infect bacteria. These viruses typically possess DNA, although some RNA bacteriophages are also known to exist.
Key takeaway
The core point to note is that a significant group of viruses, specifically RNA viruses, do not contain DNA. Instead, they use RNA for their genetic material. Although bacteriophages are mentioned, they primarily use DNA. The absence of DNA as the primary genetic material defines RNA viruses.
Table Summarizing DNA and RNA Viruses
| Feature | DNA Viruses | RNA Viruses |
|---|---|---|
| Primary Nucleic Acid | DNA | RNA |
| Examples | Herpesviruses, Poxviruses | HIV, Influenza, Poliovirus |
