What is the difference between a bacterium and an archaeon?

Question

The other day our teacher asked what makes bacteria different from archaea, and honestly, I wasn’t too sure. So I did some digging. Turns out, the difference isn’t just minor—it’s in their membranes, genes, metabolism, and even how they react to antibiotics. This answer helped everything click, especially how unique archaea really are.

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Aino 2025-06-12T18:34:14+00:00 1 Answer 1 views
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Answer ( 1 )

  1. fleming
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    2025-07-13T14:59:39+00:00
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    Cell membrane lipids

    • Bacteria: Ester‑linked fatty acid phospholipids.
    • Archaea: Ether‑linked isoprenoid chains; some species form a monolayer membrane for extra stability in extreme heat.

    Cell wall

    • Bacteria – peptidoglycan containing muramic acid.
    • Archaea – no peptidoglycan; they may have pseudo‑murein, S‑layer proteins or polysaccharides.

    Information machinery

    Archaeal RNA polymerase, promoters and ribosomal proteins resemble those of eukaryotes more than bacteria. That is why many antibiotics that block bacterial transcription or translation dont touch archaea.

    Metabolism

    Archaea include methanogens, extreme halophiles and hyperthermophiles. Bacteria cover a vast range but none produce methane.

    Pathogenicity

    Thousands of bacterial pathogens are known. So far, no archaeon has been proven to cause disease in humans.

    Antibiotic susceptibility

    Drugs targeting peptidoglycan (beta lactams) or 70 S ribosomes work on bacteria but not on archaea.

    Bottom line

    Both groups are prokaryotes, yet archaeal membranes, walls and genetic machinery are distinct enough that biologists place them in their own domain of life.

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