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Carlson2_FungiDiversity - Professor Thomas Carlson Fungi...

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1 Fungi Lectures Bio 1B, Fall 2007 Professor Thomas Carlson 2 3 Fungi Fungi are more closely related to animals than plants Fungi and Animals: Chitin in cell walls – Flagella – Store carbon by synthesizing glycogen polysaccharide Plants: Cellulose in cell walls – Store carbon by synthesizing starch polysaccharide 4 Nutrition & Habit: Land Plants: photosynthesis Fungi: absorb nutrients from living or dead organisms Animals: absorb nutrients from living or dead organisms Land Plants: do not live on or in humans Fungi: may live on and/in humans 5 Fungi have an absorptive lifestyle: Some are parasitic or mutualistic absorb nutrients from living plants, animals, humans Some are saprophytic absorb nutrients from dead/decomposing plant (Fig 31.1) and/or animal tissue recycle nutrients back into the biosphere 6 Fungi grow in two ways: multicellular mycelia e.g., mushrooms single-celled yeasts baker’s yeast, Saccharomyces cerevisiae Candida albicans (can be pathogenic in humans)
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7 Multicellular mycelium (Figs 31.2, 31.3, 31.4) composed of filaments known as hyphae Mushrooms consist of densely packed hyphae Hyphae (Figs 31.2, 31.3, 31.4) long narrow tubular filaments optimizes surface area/volume ratio which enhances absorption hyphae may be broken into compartments by septa that contain gaps which enables movement of materials between compartments 8 9 10 Saprophytic fungi: Saprophytic fungi are decomposers that reverse biosynthesis by breaking down plant and animal tissue and recycling nutrients back into the biosphere Some fungal organisms can digest wood (Fig 31.1) 11 Extracellular digestion by saprophytic fungi: Fungi secrete digestive enzymes outside of their hyphae: ! breakdown cellulose, starch, lignin, proteins, & RNA into ! smaller compounds e.g., sugars, amino acids, nucleic acids ! able to diffuse across the cell membrane into the hyphae 12 Lignin and cellulose degrading fungi play important role in global carbon cycle Lignin degradation: hyphae excrete lignin peroxidase into extracellular environment ! breaks down dense lignin matrix around long strands of cellulose Cellulose digestion: Cellulases excreted into extracellular environment breakdown cellulose
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