Q.13 Genetic material of Coronavirus is
(1) Single-stranded RNA
(2) Double-stranded RNA
(3) Single-stranded DNA
(4) Double-stranded DNA
Coronavirus, including SARS-CoV-2, has a unique genome that drives its replication and infectivity. A common exam question tests this: “Genetic material of Coronavirus is”
Correct Answer: (1) Single-stranded RNA
Coronaviruses belong to the family Coronaviridae with a positive-sense, single-stranded RNA (+ssRNA) genome, approximately 30 kb long—the largest among RNA viruses. This allows direct translation by host ribosomes upon entry.
Coronavirus Genome Details
The SARS-CoV-2 genome encodes structural proteins like spike (S), envelope (E), membrane (M), and nucleocapsid (N), plus non-structural proteins for replication. It features a 5′ cap and 3′ poly-A tail, mimicking mRNA. Mutations here, like in the spike gene, influence variants such as Omicron.
This +ssRNA structure enables rapid evolution via error-prone RNA-dependent RNA polymerase, explaining high mutation rates.
Why Single-Stranded RNA? Key Traits
Unlike DNA viruses, ssRNA viruses replicate entirely in the cytoplasm without nuclear involvement. Positive-sense means the genome acts as mRNA; negative-sense requires transcription first. Coronaviruses exemplify +ssRNA efficiency in animal and human hosts.
Option Breakdown: Other Genetic Materials
(2) Double-Stranded RNA (dsRNA)
dsRNA viruses like rotavirus (Reoviridae) form replicative intermediates during RNA synthesis. Coronaviruses lack this biphasic structure, using only ssRNA templates—no dsRNA phase dominates their lifecycle.
(3) Single-Stranded DNA (ssDNA)
ssDNA viruses, such as parvoviruses (e.g., canine parvovirus), are small, non-enveloped, and convert ssDNA to dsDNA in the nucleus. Coronaviruses are enveloped RNA viruses, bypassing DNA entirely.
(4) Double-Stranded DNA (dsDNA)
dsDNA viruses like herpesviruses use host DNA polymerase for replication. Coronaviruses, as RNA viruses, avoid DNA stages, relying on viral RdRp for all genomic copying.
Viral Genome Types: Comparison Table
| Genome Type | Examples | Key Features | Coronavirus Match? |
|---|---|---|---|
| Single-stranded RNA (+ssRNA) | Coronaviruses, Flaviviruses | Direct mRNA translation, cytoplasmic | Yes |
| Double-stranded RNA | Rotavirus, Reovirus | Segmented, replicative intermediates | No |
| Single-stranded DNA | Parvovirus, Geminivirus | Converts to dsDNA, nuclear often | No |
| Double-stranded DNA | Herpesvirus, Adenovirus | Host polymerase, large size | No |
This table highlights why only ssRNA fits Coronavirus biology.
Understanding genetic material of Coronavirus clarifies viral pathogenesis, vaccine design (e.g., mRNA vaccines mimicking its genome), and exam success in microbiology or virology.
