week 1 - fungi diversity - Fungi Instructor: Thomas Carlson...

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1 Fungi Lectures Bio 1B, Fall 2008 Instructor: Thomas Carlson 2 Fungi • Fungi are more closely related to animals than plants Fungi and Animals: Chitin in cell walls of fungi and in exoskeletons of invertebrates – Flagella – Store carbon by synthesizing glycogen polysaccharide Plants: Cellulose in cell walls – Store carbon by synthesizing starch polysaccharide 3 • 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 4 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 and/or animal tissue • recycle nutrients back into the biosphere 5 Fungi grow in two ways: • multicellular mycelia e.g., mushrooms • single-celled yeasts • baker’s yeast, Saccharomyces cerevisiae (Fig 31.7) Candida albicans (a commensal fungus living in and on humans that can be pathogenic in humans) 6 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
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7 8 9 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 10 Extracellular digestion by saprophytic fungi: Fungi secrete digestive enzymes outside of their hyphae: ! breakdown cellulose, starch, lignin, ! smaller compounds e.g., sugars, amino acids, nucleic acids ! able to diffuse across the cell membrane into the hyphae 11 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
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This note was uploaded on 09/24/2008 for the course BIO 1B taught by Professor Carlson,mischel,power during the Spring '07 term at University of California, Berkeley.

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week 1 - fungi diversity - Fungi Instructor: Thomas Carlson...

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