Chapter 12 - Fungi, Protozoa, and Multicellular parasites

Chapter 12 - Fungi, Protozoa, and Multicellular parasites -...

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Chapter 12 (Tortora) Fungi, Protozoa, and Multicellular Parasites. Microbial Genetics - Fungi, Protozoa, and Multicellular Parasites Fungi: A morphologically diverse (include yeasts, molds, and fleshy fungi) group of spore-bearing, achlorophyllus, usually non-motile organisms that possess a cell wall. General Characteristics: 1. Eukaryotic with well-defined nuclear membrane. 2. Cell wall contains glucans, mannans, and chitin but no peptidoglycan. 3. Do not contain chlorophyll. 4. All are chemoheterotrophs. 5. Most are saprobes (grow on non-living organic matter). 6. Many fungi, especially those that cause disease in humans are dimorphic. For example: Candida albican is yeast like (unicellular) at 37 degrees centigrade and mold like (filamentous) at 25 degrees centigrade. 1
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7. Most are non-motile. 8. Reproduce sexually or asexually or both. 9. Most grow best at acidic pH. 10. Most are osmophiles. 11. Capable of metabolizing complex carbohydrates such as Pectin (pectinase) and cellulose (cellulose). 12. Most molds are aerobic. Fungal Morphology 1. The body of a mold and fleshy fungus is made up of long tubular protoplasmic structures known as hyphae (singular; hypha). 2. Some yeasts are capable of producing a pseudohyphae. 2
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3. Some hyphae are divided into compartments by cross-wall structures called septa (singular, septum); while others are non septate or coenocytic (multi-nucleated hypha). 4. A mass of branching hyphae is called mycelium. Fungal Growth and Reproduction 1. Yeast cells grow by budding or fission to form daughter cell of equal size. 2. A mold reproduces asexually by budding (yeast) or by producing asexual spores or sexual spores. A Budding yeast 3
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1. Sporangiospores: are produced inside a swollen fertile structure called sporangium located at the end of a sporangiophore. Examples: Rhizopus nigrican (bread mold) Mucor stolonifer (dung mold) Sporangiospores 2. Conidiospores: are produced in a chain at the end of a conidiophore, and are not enclosed in a sac. Examples:
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Chapter 12 - Fungi, Protozoa, and Multicellular parasites -...

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