Chapter 24 FUNGI - Chapter 24 Chapter Fungi FUNGI...

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Unformatted text preview: Chapter 24 Chapter Fungi FUNGI CHARACTERISTICS FUNGI EUKARYOTIC: CONTAIN A MEMBRANE BOUND NUCLEUS EUKARYOTIC: AND ORGANELLES AND HETEROTROPHS: MUST CONSUME OTHER ORGANISMS HETEROTROPHS: FOR ENERGY AND CARBON SOURCE FOR EXTRACELLULAR DIGESTION:SECRETE ENZYMES SECRETE USUALLY MULTICELLULAR:MANY CELLED BODY MANY INTO THE ENVIRONMENT , DIGEST THEIR FOOD OUTSIDE OF THEIR BODY THEN ADSORB THE DIGESTED NUTRIENTS BODY PLAN, WITH DIFFERENT REGIONS CARRYING OUT DIFFERENT FUNCTIONS FOR THE ORGANISM DIFFERENT ALL PRODUCE SPORES:ASEXUALLY,SEXUALLY OR ASEXUALLY,SEXUALLY BOTH BOTH MOST HAVE A BODY PLAN MADE OF MOST HYPHAE HYPHAE The Mycelium The Most fungi produce a Most multicellular feeding structure called a mycelium mycelium It consists of branching It tubular cells called hyphae hyphae Cell walls contain chitin Fungal Spores Fungal Made up of one or a few cells Can resist dehydration Remain dormant until environmental Remain conditions favor germination conditions Produced asexually or sexually Fungal classification is based on Fungal type of sexual spores type Types of Sexual Spores Types Club fungi make basidiospores on the Club surface of a club-shaped cell (basidium) surface Sac fungi produce ascospores inside a Sac parent cell called an ascus parent Zygomycete hyphae fuse to produce a Zygomycete thick-walled zygospore Fungal Classification FUNGI KNOWN FROM 900 MYA 56,000 KNOWN SPECIES THREE LINEAGES BASED ON STRUCTURES PRODUCED DURING THEIR SEXUAL REPRODUCTION: ZYGOMYCETES: FORM A ZYGOSPORE ASCOMYCETES: FORM AN ASCUS,(SAC) BASIDIOMYCETES: FORM A CLUB LIKE STRUCTURE (A BASIDIUM) ZYGOMYCETES ASCOMYCETES SAC FUNGI CLUB FUNG BASIDIOMYCE CHYTRIDS MICROSPORIDIANS THE IMPERFECT FUNGI(DEUTEROMYCETES) FUNGI ARE NOT YET CLASSIFIED BECAUSE THE SEXUAL STAGE HAS NOT BEEN OBSERVED amoeboid ancestors Fig. 24-2, p.392 Life Cycle of Rhizopus:Zygomycetes zygospore (2n) nuclear fusion Diploid Stage Haploid Stage meiosis spores (n) a zygospore mycelium develops from germinated spore b spore sac germinating zygospore young zygospore gametangia fusing spores (n) contact between hyphae of two mating strains stolon ASEXUAL REPRODUCTION (mitosis) rhizoids Rhizopus A bread mold Fig. 24-6a, p.394 Example of Sac Fungus Example ASCOMYCETES Most diverse group Most (30,000 species) (30,000 Produce asexual spores Produce called conidia called Produce sexual Produce ascospores in sacascospores shaped cells call asci Multicelled species form Multicelled reproductive structures called ascocarps that enclose the asci enclose Ascospores on the inner cup surface scarlet cup fungus MOREL 24-8, p.396 Fig. Club Fungus Life Cycle Hyphal cells of two mating strains meet Hyphal Cytoplasm fuses to form dikaryotic mycelium Reproductive structure (basidiocarp) forms Spore-bearing structures form on basidiocarp Nuclei fuse to produce a zygote Zygote undergoes meiosis to produce haploid spores Spores give rise to haploid mycelia Club Fungus Life Cycle nuclear fusion Diploid Stage:Basidium Haploid Stage meiosis clubshaped structures with two nuclei (n + n) gills cap stalk Spores (n) form Spores released Germination, mycelium forms “dikaryotic” (n + n) mycelium cytoplasmic fusion Fig. 24-7, p. 407 Imperfect Fungi Imperfect Species have never been observed to form Species sexual spores sexual Many do make asexual spores in many ways Some are Predatory: Arthrobtrys dactyloides Some Arthrobtrys captures prey in nooselike hyphae captures Fungal Foes Fungal Small proportion are plant pathogens: Small plant Ascomycetes are responsible for Chestnut blight, Dutch elm disease,Apple scab Dutch Basiomycetes cause smuts of cereal grains, spoil other food supplies other Tiny minority adversely affect human health: Tiny Ergotism, some are poisonous “toad stools”, Human pathogens such as “Yeast infections, Human Athletes foot, Ringworm, Histoplasmosis, Athletes Destroy other products: mildew on the shower mildew curtain BENEFICIAL FUNGI BENEFICIAL AS MUTUALISTIC SYMBIONTS ANTIBIOTICS FOOD EXTRACTS FOR FOOD AS DECOMPOSERS AS ENVIRONMENTAL INDICATORS FOOD AND ANTIBIOTICS FOOD SOME ARE EATEN DIRECTLY:MUSHROOMS, MUSHROOMS, MORELS, PORTABELLAS, BLUE CHEESE MORELS, IN SOME THE EXTRACTS ARE USED: CITRIC ACID, CARBON DIOXIDE AND ALCOHOL FROM YEAST, CITRIC ANTIBIOTICS FROM PENICILLIUM USED IN GENETIC ENGENEERING Fungi as Decomposers Fungi Break down organic compounds in their Break surroundings surroundings Carry out extracellular digestion and Carry absorption absorption Plants benefit because some carbon and Plants nutrients are released nutrients Keep dead organisms and debris from Keep piling up in the ecosystem piling MUTUALISTIC FUNGI MUTUALISTIC MYCORRHIZAE “Fungus-root” LICHENS: Combination of a fungus and a LICHENS: photosynthetic algae or cyanobacteria(Combination of fungus and cyanobacteria(Combination photosynthetic organism(s) photosynthetic Mutualism between a fungus and Mutualism a tree root tree Fungus gets sugars from plant Plant gets minerals from fungus Many plants do not grow well Many without mycorrhizae without Organisms are symbionts Relationship is a mutualism Survive in hostile habitats and colonize new Survive habitats: Pioneer organism of a new habitat habitats: Absorb mineral ions from substrates, die Absorb and leave “soil” and Cyanobacteria-containing lichens can fix Cyanobacteria-containing nitrogen nitrogen Convert atmospheric nitrogen to a form Convert plants can use plants MYCORRHAZAE & LICHENS MYCORRHAZAE Early Warning Systems Early Lichens are very Lichens sensitive to deteriorating environmental conditions conditions Absorb toxins but Absorb cannot get rid of them them Can serve as Can environmental indicators indicators Numbers and kinds of Numbers mushrooms are declining declining Decline correlates Decline with rising air pollution with If the fungal If symbionts of trees and other plants are killed, ecosystems will be disrupted ...
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This note was uploaded on 12/02/2009 for the course SCI 013 taught by Professor Xxx during the Fall '09 term at Purdue University Calumet.

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