Characteristics / Properties of Viruses and General Structure of Viruses

Are viruses cellular or acellular?

Infectious, acellular pathogens.

Are viruses obligate or facultative parasites?

Obligate intracellular parasites with host and cell‑type specificity.

What type of genome do viruses have?

DNA or RNA (never both).

What surrounds the viral genome?

A protein capsid.

What additional structure may some viruses have?

A phospholipid envelope with viral glycoprotein spikes.

Do viruses have genes for reproduction?

No — they must exploit host‑cell genomes.

What organisms do viruses infect?

All types of organisms.

What is a nucleocapsid?

Capsid + nucleic acid.

What is a naked virus?

Virus without an envelope.

What is an enveloped virus?

Virus with a lipid envelope around the capsid.

What are spikes made of?

Glycoproteins.

What are spikes used for?

Attachment to host cells.