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Unformatted text preview: Lecture 15 - Cutaneous and Opportunistic Fungal I nfections M I-34a. List the differences between yeasts and molds regarding macroscopic and microscopic appearance and mode of replication General Class: Fungi • Widely distributed in nature (air, water, soil, decaying organic matter) • Break down dead plant tissue • About 400,000 species • Facultative anaerobe/strict aerobe • Non are strict anaerobe Structures: • Stalk – mycelia (nutrients) • the vegetative part – form by mass of hyphae • Spores – are the reproductive units • The wind blows the spores and spread them (the daughter will grow up away from the fungus) • conidiophores – specialized structure for holding spores • conidio - spores • Cell Wall (usually very thick cell wall) • Glucan- beta (alpha) linked glucose • Mannan- alpha linked mannose • Chitin- beta linked N-acetylglucosamine • Cell wall had multi layer – with different types of carbohydrates • Membrane • Primary sterol is ergosterol rather than cholesterol • The reason for the majority of the antifungal drugs • They inhibit the synthesis of ergosterol more than cholesterol • This difference is the basis for two classes of anti-fungal drugs • Amphotericin B (binds to ergosterol and destablizes the membrane) • Imidazoles • Mycelia • Vegetative • Undifferentiated , form early , grow into media to obtain nutrients • nutrition • Aerial • Bear spores , form later , grow up into the air • reproduce- ***Spores are like the seeds of plants - a form to allow movement of the organism in the environment Nutrients: fungi grow into their food! • Most often live on dead organic matter • They secrete enzymes that break down complex carbohydrates and proteins • Do NOT photosynthesize Ubiquitous!! Found everywhere • Fungi are the most common organisms in the air we breathe • We are all exposed to fungi on a daily basis • Those who live in a moldy environment are more exposed than others • Fungi are not spread person to person Fungi = Eukaryotes • 80S ribosomes (they are more like us) • Membrane bound organelles • Sterols in cytoplasmic membranes • Multiple linear chromosomes Sexual orientation and name • Most, but not all, fungi have a sexual form • Fungi typically look different in the sexual vs the asexual state • Mycologists give the sexual state a different name than the asexual state • We will use the asexual names in this course Yeasts Molds M icroscopic- Sabauraud Agar : Colony --- like bacteria (smooth colonies)- black center clear space around it = capsule- Sabauraud Agar : Colony – fuzzy (mold grows up into the air, WET) Macroscropic- Do not have specialized structures- forms spores (conidia ) in environment and culture - require spore formation (sporulation)- Special structure (mycelia, spores)- Mode of replication Budding- Through YMC (yeast mother cell) Ph (pseudohypae – a daughter cell)- Daughter cells significantly smaller than...
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This note was uploaded on 09/14/2011 for the course PHARM mb taught by Professor Staff during the Spring '11 term at UCSD.
- Spring '11