What is the difference between a bacterium and a fungus?

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I remember our professor asking about the difference between bacteria and fungi, and it got me thinking. Turns out, the differences are huge—from how their cells are built to the way they get energy and reproduce. Bacteria are prokaryotes, fungi are eukaryotes, and that changes everything. I read more and was surprised at how distinct they really are.

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Anttilampinen 2025-06-01T19:38:10+00:00 1 Answer 3 views
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  1. fleming
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    2025-06-01T19:39:25+00:00
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    Bacteria are prokaryotic organisms. Their cells lack membrane-bound organelles, including a true nucleus. Their genetic material, usually a single circular chromosome, resides in the cytoplasm in a region called the nucleoid.

    Fungi are eukaryotic, meaning their cells contain membrane-bound organelles like a true nucleus, mitochondria, endoplasmic reticulum, and Golgi apparatus.

    Cell Wall Composition

    • Bacteria: Cell walls contain peptidoglycan. Gram-positive bacteria have thick peptidoglycan layers, while Gram-negative bacteria have thinner layers with an outer membrane containing lipopolysaccharides.
    • Fungi: Cell walls contain chitin, glucans, and mannoproteins. They do not contain peptidoglycan.

    Size and Structure

    • Bacteria: Typically range from 0.2 to 2.0 micrometers in diameter.
    • Fungi: Generally larger. Yeasts (unicellular fungi) are 3 to 5 micrometers, and filamentous fungi form hyphae. Some develop complex multicellular fruiting bodies like mushrooms.

    Genetic Organization and Reproduction

    • Bacteria: Small genomes (1-5 million base pairs), reproduce asexually via binary fission. Genetic diversity arises through mutation and horizontal gene transfer (conjugation, transformation, transduction).
    • Fungi: Larger genomes (10–40 million base pairs or more), reproduce both asexually (budding, spores) and sexually (meiosis and mating type fusion).

    Metabolism

    • Bacteria: Metabolically diverse. Some are autotrophs (photoautotrophs and chemoautotrophs), using compounds like hydrogen, sulfur, and ammonia for energy.
    • Fungi: Exclusively heterotrophic. They secrete enzymes externally to digest complex materials like lignin and cellulose, then absorb the breakdown products.

    Ecological Roles

    • Bacteria: Key players in nutrient cycling (nitrogen fixation, nitrification, denitrification, sulfur metabolism). Found in all environments including extreme ones.
    • Fungi: Important decomposers in terrestrial ecosystems. Also form symbiotic relationships with plants (mycorrhizae) and algae/cyanobacteria (lichens).

    Medical Significance

    • Bacteria: Often cause acute infections that respond to antibiotics (e.g., Streptococcus pneumoniae, E. coli, Mycobacterium tuberculosis).
    • Fungi: Often cause chronic infections, especially in immunocompromised individuals. Treated with antifungals targeting ergosterol synthesis or chitin formation (e.g., Candida albicans, Aspergillus fumigatus, Cryptococcus neoformans).

    Industrial and Biotechnological Applications

    • Bacteria: Used in producing antibiotics, enzymes, vitamins, and fermented foods. Crucial in recombinant DNA technology due to ease of genetic manipulation.
    • Fungi: Important for food production (bread, beer, wine), enzyme production, and pharmaceuticals (e.g., penicillin from Penicillium). Produce bioactive secondary metabolites.

    Source: Brock Biology of Microorganisms; Fungal Biology (textbook)

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