BRAINCAKENegative ssRNA Viruses
In negative-sense single-stranded RNA (−ssRNA) viruses, the genome is complementary to mRNA. It cannot be read by ribosomes, so it must first be copied into positive-sense mRNA before any viral protein can be made.
Host cells have no enzyme that can do this. The virus therefore carries its own RNA-dependent RNA polymerase inside the virus particle, packaged with the genome. Without this enzyme, the virus could not start an infection.
The stages of replication are:
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Key terms in this lesson
- rna-dependent rna polymerase
- A viral enzyme that synthesises a complementary strand of RNA using an RNA strand as the template; also called RNA replicase.
More in Prokaryotic Cells
- DNA Virus Latency
- DNA Virus Lytic Pathway
- RNA Virus Replication
- Positive ssRNA Viruses
- Retrovirus Replication
- Viruses and Disease
- The Spread of Viral Diseases
- Treating Viral Diseases
All 31 lessons in Prokaryotic Cells · All Edexcel AS-level Biology topics