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Lec.1 Mycology خلود حمدان.د INTRODUCTION TO MYCOLOGY The term "mycology" is derived from Greek word "mykes" meaning mushroom. Therefore mycology is the study of fungi. Fungi its protests eukaryotic cells non–photosynthetic microorganism. General properties of fungi: 1- They are eukaryotic; cells contain membrane bound cell organelles including nuclei, mitochondria, Golgi apparatus, endoplasmic reticulum, lysosomes etc. 2- Have ergo sterols in their membranes and possesses 80S ribosomes. 3- Have a rigid cell wall made of chitin therefore non-motile. 4- Are chemo heterotrophs (require organic compounds for both carbon and energy sources) and fungi lack chlorophyll and are therefore not autotrophic. In nutrition. 5- Fungi are osmotrophic; they obtain their nutrients by absorption. 6- They obtain nutrients as saprophytes (live off of decaying matter) or as parasites (live off of living matter). 7- All fungi require water and oxygen and there are no obligate anaerobes. 8- Typically reproduce asexually and/or sexually by producing spores. 9- They grow either reproductively by budding or non-reproductively by hyphae tip elongation. 10- Food storage is generally in the form of lipids and glycogen. Comparison between bacterial cell and fungal cell. properties Bacteria cell Fungi cell Type of cell Prokaryotic single cell Eukaryotic single cell or multi cellular cells Typical size 1-10 um 10-100nm Type of nucleus nucleotide region, without nuclear membrane Real nucleus with double membrane. Sensitive to antibiotic Sensitive to penicillin, tetracycline and chloromphincol Resistance to penicillin, tetracycline and chloromphincol Cell wall Thin,compoced of muramic acid and don’t have glucose polymers rigid cell wall made of chitin and have glucose polymers Ribosome’s 30s-50s 70s-80s Cell membrane Don’t have ergo sterols Have ergo sterols Mitochondria None One to several thousand. Chromosomes Single chromosomes, no connected with protein Multi chromosomes connected with protein PH More than 6 Less than 6 Cell division simple division mitosis ,meiosis Classification of fungi: There are three types of classification in fungi:1- Based on Sexual reproduction: Fungi reproduce by many means including budding, fission or sporulation spores can be produced asexually or sexually therefore fungal classified due do the type of spores in to:1. Zygomycetes: which produce through production of zygospores. 2. Ascomycetes: which produce endogenous spores called ascosporic in cells called asci. 3. Basidiomycetes: which produce exogenous spores called basidiospores in cells called basidia. 4. Deuteromycetes fungi that are not known to produce any sexual spores (ascosporic or basidiospores). This is a heterogeneous group of fungi where no sexual reproduction has yet been demonstrated. 2- Based on Morphology: 1. Moulds (Molds): Filamentous fungi multicelluler Eg: Aspergillus sps, Trichophyton rubrum 2. Yeasts: Single cells that buds Eg: Cryptococcus neoformans, Saccharomyces cerviciae 3. Yeast like: Similar to yeasts but produce pseudohyphae Eg: Candida albicans 4. Dimorphic: Fungi existing in two different morphological forms at two different environmental conditions. They exist as yeasts in tissue and in vitro at 37oC and as moulds in their natural habitat and in vitro at room temperature. 3- Based on side of infection . 1-Superficial mycoses like tinea nigra 2-cutaneous mycoses like candida and tinea pedis. 3-subcutaneaus mycoses like sporotrichosis. 4-Systemic mycosis like histoplasma . 5-oportunistic mycoses like Aspergillus. Morphology of fungi: Fungi exist in two fundamental forms; the filamentous (hyphal) and single celled budding forms (yeast). But, for the classification sake they are studied as moulds, yeasts, yeast like and dimorphic fungi. All fungi have typical eukaryotic morphology. They have rigid cell wall composed of chitin, which may be layered with maltose, glucose and other polysaccharides in association with polypeptides. Some lower fungi possess cellulose in their cell wall. Some fungi such as Cryptococcus and yeast form of Histoplasma capsulatum possess polysaccharide capsules that help them to evade phagocytosis. Inner to the cell wall is the plasma membrane that is a typical bi-layered membrane in addition to the presence of sterols. Fungal membranes possess ergo sterol in contrast to cholesterol found in mammalian cells. The cytoplasm consists of various organelles such as mitochondria, golgi apparatus, ribosome’s, endoplasmic reticulum,lysosomes, microtubules and a membrane enclosed nucleus. A unique property of nuclear membrane is that it persists throughout the metaphase of mitosis unlike in plant and animal cells where it dissolves and re-forms. The nucleus possesses paired chromosomes. Beneficial Effects of Fungi: 1-. Decomposition - nutrient and carbon recycling. 2. - Biosynthetic factories. The fermentation property is used for the industrial production of alcohols, fats, citric, oxalic and gluconic acids. 3.- Important sources of antibiotics, such as Penicillin. 4. Model organisms for biochemical and genetic studies. Eg: Neurospora crassa 5. Yeasts provide nutritional supplements such as vitamins and cofactors. 6. Penicillium is used to flavor Roquefort and Camembert cheeses. Harmful Effects of Fungi: 1. Destruction of food, lumber, paper, and cloth. 2. Animal and human diseases, including allergies. 3. Toxins produced by poisonous mushrooms and within food (Mycotoxicosis). 4. Plant diseases. 5. Spoilage of agriculture produce such as vegetables . .