Genomic RNA is the viral RNA molecule that carries the complete genetic information of certain viruses, serving as both the genome and, in many cases, the messenger RNA (mRNA) within infected cells.
Here's a more detailed breakdown:
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Viral Genome: The genomic RNA functions as the blueprint for producing new viral particles. It contains all the necessary genetic information for viral replication and assembly.
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mRNA Function: In many RNA viruses, the genomic RNA also acts as mRNA. This means the host cell's ribosomes can directly translate the genomic RNA into viral proteins.
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Structure:
- The genomic RNA typically contains a single long Open Reading Frame (ORF), which encodes for all viral proteins.
- It's flanked by 5′- and 3′-terminal non-coding regions (NCRs) that are crucial for genome replication and translation.
- These NCRs often form specific secondary structures, such as stem-loops, which are essential for viral processes.
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Examples: Many RNA viruses, including those in families like Picornaviridae and Flaviviridae, utilize genomic RNA that functions as mRNA. Examples include Poliovirus, Hepatitis C virus, and Zika virus.
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Significance: Understanding the structure and function of genomic RNA is critical for developing antiviral therapies. Targeting the NCRs or the ORF can disrupt viral replication and protein synthesis.
In essence, genomic RNA is a versatile molecule that serves as both the virus's genetic material and the template for protein production within a host cell.
