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Biology (Year 12) - Infectious Disease

Ben Whitten

What are fungi? The world of fungi varies greatly! From whole mushrooms to minute forms, these microscopic fungi include unicellular yeasts and moulds. They are similar to plant organisms with cell walls, however their cell walls differ in terms of what they contain.

What is the structure of fungi? Fungi are eukaryotes whose cells have membrane-bound organelles, including a nucleus. Fungi have cell walls which are made of chitin as opposed to cellulose in plant cells. Most fungi do not have flagella, however their spore form usually does which assists them to be propelled through water (a zoospore). Single-celled fungi are generally larger in comparison to bacteria, and most fungi grow multicellular filament which play a key role in their obtaining of food. Filaments are long and thin, increasing the surface area of the fungal cell for increased absorption; similarly to that of villi in the small intestine! The network of small filaments which is formed is called hyphae, which have strong, tubular cell walls surrounding the cell membrane of each cell. Hyphae grow to form mycelium, which is an interwoven mass. The mycelium is what makes up most of the body of the fungus. How do fungi replicate? A mycelium has the ability to infiltrate the tissues of the host in which it feeds on. Most pathogenic fungi produce spores, which can be done through means of sexual reproduction or asexual reproduction. The mature mycelium forms sporangia, which release spores. When these spores make contact with a new, moist food source, they may germinate to form a new mycelium.

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