2. Introduction of Fungi They are classified as eukaryotes , Fungi can be divided into two basic morphological forms, yeasts and hyphae Yeasts are unicellular fungi which reproduce asexually by blastoconidia formation (budding) or fission Hyphae are multi-cellular fungi which reproduce asexually and/or sexually
3. Most fungi occur in the hyphae form as branching, threadlike tubular filaments. - lack cross walls ( coenocytic ) - have cross walls ( septate ) - clamp connections at the septa which connect the the hyphae elements. Coenocytic hyphae Septated Hyphae
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5. COMMON CHARACTERISTICS OF FUNGI 1. Heterotrophy - 'other food'. There are three major categories of heterotrophs, which include the saprophytes , symbionts , and parasites . Saprophytes (feed on dead tissues or organic waste); symbionts (mutually beneficial relationship between a fungus and another organism); parasites (feeding on living tissue of a host). Parasites that cause disease are called pathogens . Some parasites are obligate parasites (require a living host to survive), while others are facultative or nonobligate parasites (do not require a living host in order to survive). 2. Body form unicellular filamentous (tube-like strands called hypha (singular) or hyphae (plural). mycelium = aggregate of hyphae sclerotium = hardened mass of mycelium that generally serves as an overwintering stage. multicellular , such as mycelial cords, rhizomorphs, and fruit bodies (mushrooms)
6. 3. Fungus is often hidden from view . It grows through its food source (substratum), excretes extracellular digestive enzymes, and absorbs dissolved food. 4. Indeterminate growth . 5. Spores - asexual (product of mitosis) or sexual (product of meiosis) in origin. Purpose of Spores (a) Allows the fungus to move to new food source. (b) Resistant stage - allows fungus to survive periods of adversity. (c) Means of introducing new genetic combinations into a population. 6. Vegetative phase of fungus is generally sedentary. 7. Cell wall present, composed of cellulose and/or chitin.
7. 8 . Food storage - generally in the form of lipids and glycogen. 9. Eukaryotes - true nucleus and other organelles present. 10. All fungi require water and oxygen (no obligate anaerobes). 11. Fungi grow in almost every habitat imaginable, as long as there is some type of organic matter present and the environment is not too extreme. 12. Diverse group, number of described species is about 69,000 (estimated 1.5 million species total).
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13. Asexual Reproduction: -spores are produced by sporangia at the ends of modified, erect hyphae Sexual Reproduction : -two opposite mating types of hyphae join to produce gametangia that produce a diploid zygospore (thick walled spore) -the zygospore undergoes meiosis before germination and produces a haploid mycelium
14. D. CELL WALLS : Chitin and chitosan. E. ECOLOGY: Free-living to parasitic. Free-living forms mainly terrestrial saprobes. Parasites mainly of insects, but of other animals, too. Some parasitic on microbial eukaryotes.