BRAINCAKERNA Virus Replication
RNA viruses face a problem that DNA viruses do not. Host cells copy DNA into DNA (DNA polymerase) and DNA into RNA (RNA polymerase), but they have no enzyme to copy RNA from an RNA template. An RNA virus must therefore provide its own.
Most RNA viruses code for an RNA-dependent RNA polymerase, also called RNA replicase. This enzyme reads a strand of RNA and builds a complementary RNA strand using free host RNA nucleotides. It is used both to make viral mRNA and to copy the viral genome.
Copying always involves a complementary intermediate. A genome strand is used as a template to make a complementary strand, and that strand is then used as a template to make new genome copies:
Sign in free to see the rest of this lesson, the R.E.C.I.P.E. recall steps and the quiz
BrainCake is free. Make an account in seconds and pick up where this page stops.
Key terms in this lesson
- proofreading
- The correction of errors during nucleic acid synthesis, when an enzyme checks and replaces incorrectly paired bases.
More in Prokaryotic Cells
- Viral Reproduction
- Virus Life Cycle
- DNA Virus Latency
- DNA Virus Lytic Pathway
- Positive ssRNA Viruses
- Negative ssRNA Viruses
- Retrovirus Replication
- Viruses and Disease
All 31 lessons in Prokaryotic Cells · All Edexcel AS-level Biology topics