Viruses: Living or Nonliving? (Leaving Cert Biology): Revision Notes

Viruses: Living or Nonliving?

• Viruses are obligate parasites - they can only replicate when in a host cell.

Are Viruses Living or Nonliving?

• Viruses are not cells as they do not contain membranes or cell organelle.
• They are not a member of any of the five kingdoms of living things.
• Viruses are on the border between living and non-living things.

Living Features	Nonliving Features
Viruses have nucleic acid (DNA or RNA)	Viruses have only one type of nucleic acid (either DNA or RNA). Living things have both.
Viruses can replicate and pass on genetic information.	Viruses cannot reproduce on their own. They require a host cell to replicate.
Viruses have a protein coat.	Viruses do not have any organelle (no ribosomes, no mitochondria etc.)
	Viruses cannot respire or feed.