Which statement accurately describes the viral capsid?

Which statement accurately describes the viral capsid?

• A. It is the lipid envelope surrounding the genome.
• B. It is the site of transcription in the host cell.
• C. It is composed of nucleotides that encode the coat.
• D. It is the protective protein coat formed by coat proteins.

Answer: (D)

The key idea is what the viral capsid actually is and what it’s made from. The capsid is the protective protein coat that encases the viral genome, built from protein subunits called coat or capsid proteins. That protein shell serves to protect the genome and help deliver it into a host cell. That’s why the statement about the capsid being a lipid envelope isn’t right—lipid envelopes are a separate, lipid-based outer layer found in enveloped viruses, not the protein shell itself. The notion that the capsid is the site of transcription in the host cell isn’t correct either, since transcription occurs inside the host cell after the genome is delivered, using viral or host enzymes, not within the capsid. Finally, saying the capsid is composed of nucleotides that encode the coat confuses the genome’s building blocks with the protein shell; nucleotides form nucleic acids that encode proteins, but the capsid itself is made of proteins, not nucleotides.

The key idea is what the viral capsid actually is and what it’s made from. The capsid is the protective protein coat that encases the viral genome, built from protein subunits called coat or capsid proteins. That protein shell serves to protect the genome and help deliver it into a host cell.

That’s why the statement about the capsid being a lipid envelope isn’t right—lipid envelopes are a separate, lipid-based outer layer found in enveloped viruses, not the protein shell itself. The notion that the capsid is the site of transcription in the host cell isn’t correct either, since transcription occurs inside the host cell after the genome is delivered, using viral or host enzymes, not within the capsid. Finally, saying the capsid is composed of nucleotides that encode the coat confuses the genome’s building blocks with the protein shell; nucleotides form nucleic acids that encode proteins, but the capsid itself is made of proteins, not nucleotides.