• Question: Are there living organisms without cells?

    Asked by Ana María to Eoin, Ester, Ildiko, Natasha, Paul, Tom on 6 Nov 2017. This question was also asked by 273cesk28.
    • Photo: Paul McKeegan

      Paul McKeegan answered on 6 Nov 2017:

      Nope!

      There are viruses, which aren’t really cells, and they’re not really alive either. They need to be inside a proper cell to be able to make copies of themselves.

      There are bacteria and archaea, single-‘celled’ organisms which have very different cells to our own. Animal and plant cells are called eukaryotes, which means true nucleus. Bacteria and archaea are prokaryotes, which have DNA, but it is in a circle rather than a double helix, and not inside a nucleus.

      But I don’t think there are any living creatures on Earth (or Mars!?) without cells at all.

    • Photo: Ester Gil Vazquez

      Ester Gil Vazquez answered on 6 Nov 2017:

      Hi! good point. The answer is no, cell are the basic units of life. They are the building blocs of all living things. I’ll give a piece of info that I have always found interesting: you could think that viruses are alive: they move around, infect, divide… However, they are not classified as living things. Why is that? there are many little reasons, but mainly they are not made of cells and still depend on cells to keep on existing (they can not divide outside a cell).

    • Photo: Eoin McKinney

      Eoin McKinney answered on 6 Nov 2017:

      I agree the answer is ‘no’…. but….. some ‘things’ have interesting properties that mean they almost fit our current definitions of being alive. Most people wouldn’t consider viruses as being ‘alive’ as they can’t independently perform all necessary functions outside of another living cell. They do have RNA/DNA, replicate and evolve though. Another controversial example are proteins called prions. They aren’t ‘alive’ either – they’re misfolded proteins – but they can cause other proteins to misfold, too, so they do effectively replicate themselves. The fundamental question underlying your (very intereseting) question is ‘what do we mean when we say something is ‘alive’?’. Our current definitions exclude viruses, but those definitions are just a convention…. you could make a case that they are wrong and viruses are alive after all………

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