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IV. Fungi KNOW RED STUFF A. Overview 1. General Characteristics - multicellular eukaryotes - heterotrophic - absorptive nutrition: excrete enzymes into.

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Presentation on theme: "IV. Fungi KNOW RED STUFF A. Overview 1. General Characteristics - multicellular eukaryotes - heterotrophic - absorptive nutrition: excrete enzymes into."— Presentation transcript:

1 IV. Fungi KNOW RED STUFF A. Overview 1. General Characteristics - multicellular eukaryotes - heterotrophic - absorptive nutrition: excrete enzymes into environment and absorb the product of that digestion. They digest dead matter (decomposers) or live matter (pathogens), or may be symbiotes.

2 IV. Fungi 2. Classification - Chytridiomycota - Zygomycota - Ascomycota - Basidiomycota Single celled members of these groups are all called “yeasts”. They are distinguished from protists based on a chitinous cell wall and absorptive (rather than phagocytic) nutrition.

3 IV. Fungi 3. General Biology - The organism is composed of threadlike “hyphae”

4 IV. Fungi 3. General Biology - The organism is composed of threadlike “hyphae” - The hypha can be coenocytic (without divisions) or septate (with incomplete cell walls between)

5 IV. Fungi 3. General Biology - The organism is composed of threadlike “hyphae” - The hypha can be coenocytic (without divisions) or septate (with incomplete cell walls between) - These have a huge surface area/volume ratio for absorption. - The largest organisms known… 37 acres.

6 IV. Fungi 4. Ecological Roles - decomposers: Fungi decompose lignin and cellulose, which most free-living bacteria can’t digest.

7 IV. Fungi 4. Ecological Roles - decomposers: Fungi decompose lignin and cellulose, which most free-living bacteria can’t digest. * antibiotics

8 IV. Fungi 4. Ecological Roles - decomposers: Fungi decompose liginin and cellulose, which most free-living bacteria can’t digest. * antibiotics - mycorrhizae: fungal symbiotes of certain plants. The fungus increases the absorbance area of roots dramatically, and passes water and nutrients to the plant. The plant feeds the fungus with glucose.

9 IV. Fungi 4. Ecological Roles - decomposers: Fungi decompose liginin and cellulose, which most free-living bacteria can’t digest. * antibiotics - mycorrhizae: fungal symbiotes of certain plants. The fungus increases the absorbance area of roots dramatically, and passes water and nutrients to the plant. The plant feeds the fungus with glucose. - lichens – symbiote with alga

10 IV. Fungi 4. Ecological Roles - decomposers: Fungi decompose liginin and cellulose, which most free-living bacteria can’t digest. * antibiotics - mycorrhizae: fungal symbiotes of certain plants. The fungus increases the absorbance area of roots dramatically, and passes water and nutrients to the plant. The plant feeds the fungus with glucose. - lichens – symbiote with alga - pathogens – Athlete’s foot, ringworm, yeast infections - parasites – entomophagous fungi

11 IV. Fungi B. Zygomycetes - coenocytic hypha - asexual reproduction haploid hypha produces sporangia and releases spores.

12 IV. Fungi B. Zygomycetes - sexual reproduction – hypha touch, and produce gametangia. Gametes produced inside – fusion into dikaryotic cells (2 nuclei). Each dikaryon then becomes diploid (fusion of nuclei and undergoes meiosis. Spores are released. - many are imporant mycorrhyzal symbionts.

13 IV. Fungi C. Ascomycetes - septate hypha

14 IV. Fungi C. Ascomycetes - septate hypha - characterized by production of spore-bearing “asci”

15 IV. Fungi C. Ascomycetes - septate hypha - characterized by production of spore-bearing “asci” - baker’s yeast (levening and fermentation) - molds – pathogens of plants such as Aspergillus, Penicillium, Neurospora, Chestnut Blight, Dutch Elm disease, etc.

16 IV. Fungi C. Ascomycetes - life cycle

17 IV. Fungi D. Basidiomycetes - bear puffballs or mushrooms as fruiting bodies

18 IV. Fungi D. Basidiomycetes - bear puffballs or mushrooms as fruiting bodies - haploid hyphae fuse in dikaryotic hyphae.

19 IV. Fungi D. Basidiomycetes - bear puffballs or mushrooms as fruiting bodies - haploid hyphae fuse in dikaryotic hyphae. - these dikaryotic hyphae form the fruiting structure.

20 IV. Fungi D. Basidiomycetes - bear puffballs or mushrooms as fruiting bodies - haploid hyphae fuse in dikaryotic hyphae. - these dikaryotic hyphae form the fruiting structure. - at the tip of each hyphae, the basidium forms, in which meiosis occurs to produce new haploid spores.

21 - life cycle

22 Characteristics of Fungal Hyphae: Septate versus Coenocytic

23 Mycelium: Large, Visible Mass of Hyphae

24 IMPORTANT DIVISIONS OF FUNGI 1. Deuteromycota u Not known to produce sexual spores. u Reproduce asexually. u Catch-all category for unclassified fungi: –Pneumocystis carinii: Causes pneumonia in AIDS patients. Leading cause of death in AIDS patients. Originally classified as a protozoan. – Candida albicans: Causes yeast infections of vagina in women. Opportunistic infections of mucous membranes in AIDS patients.

25 Opportunistic Infection by Candida albicans in an AIDS Patient Source: Atlas of Clinical Oral Pathology, 1999

26 Life Cycle of Eupenicillium (Ascomycete) Reproduces Asexually and Sexually

27 Severe nail infection with Trichophyton rubrum in a 37-year-old male AIDS patient. Source: Intern. J. Dermatol. 31(1992): 453.

28 Disseminated Histoplasma capsulatum, skin infection. Source: Microbiology Perspectives, 1999.

29 FUNGAL DISEASES Mycosis: Any fungal disease. Tend to be chronic because fungi grow slowly. Mycoses are classified into the following categories: I. Systemic mycoses: Fungal infections deep within the body. Can affect a number if tissues and organs. u Usually caused by fungi that live in the soil and are inhaled. Not contagious. u Examples: –Histoplasmosis (Histoplasma capsulatum): Initial infection in lungs. Later spreads through blood to most organs. –Coccidiomycosis (Coccidioides immites): Resembles tuberculosis.

30 Systemic Mycosis: Histoplasmosis Disseminated Histoplasma capsulatum, lung infection. Source: Microbiology Perspectives, 1999.

31 FUNGAL DISEASES (Continued) II. Cutaneous mycoses: Fungal infections of the skin, hair, and nails. u Secrete keratinase, an enzyme that degrades keratin. u Infection is transmitted by direct contact or contact with infected hair (hair salon) or cells (nail files, shower floors). u Examples: – Ringworm (Tinea capitis and T. corporis) – Athlete’s foot (Tinea pedis) – Jock itch (Tinea cruris)

32 Cutaneous Mycosis Ringworm skin infection: Tinea corporis Source: Microbiology Perspectives, 1999

33 Cutaneous Mycosis Candida albicans infection of the nails. Source: Microbiology Perspectives, 1999.

34 FUNGAL DISEASES (Continued) III. Subcutaneous mycoses: Fungal infections beneath the skin. u Caused by saprophytic fungi that live in soil or on vegetation. u Infection occurs by implantation of spores or mycelial fragments into a skin wound. u Can spread to lymph vessels. IV. Superficial mycoses: Infections of hair shafts and superficial epidermal cells. Prevalent in tropical climates.

35 FUNGAL DISEASES (Continued) Opportunistic mycoses: Caused by organisms that are generally harmless unless individual has weakened defenses: – AIDS and cancer patients – Individuals treated with broad spectrum antibiotics – Very old or very young individuals (newborns). u Examples: –Aspergillosis: Inhalation of Aspergillus spores. –Yeast Infections or Candidiasis: Caused mainly by Candida albicans. Part of normal mouth, esophagus, and vaginal flora.

36 ECONOMIC IMPORTANCE OF FUNGI u 25-50% of harvested fruits and vegetables are damaged by fungi. u Fungal infections of plants are commonly called rots, rusts, blights, wilts, and smuts. –Phytophthora infestans: Caused great potato famine in mid- 1800s. Over 1 million people died from starvation in Ireland. Many immigrated to the U.S. u Beneficial fungi: –Candida oleophila: Prevents fungal growth on harvested fruits. –Saccharomyces cerevisiae: Used to make bread and wine. –Genetically engineered yeast strains are used to make proteins (Hepatitis B vaccine). –Taxomyces: Produces anticancer drug taxol. – Trichoderma: Produces cellulase. Used to make fruit juice.


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