The Eukaryotic Members of the Microbial World

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The Eukaryotic Members of the Microbial World

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1. The Eukaryotic Members of the Microbial World Chapter 12

2. Algae Diverse group of eukaryotic organisms Use light to convert carbon dioxide and water to carbohydrates Includes both microscopic unicellular and macroscopic multicellular organisms

3. Algae Classification of algae Algae not a distinct classification term Grouped for identification based on numerous properties Photosynthetic pigments Cell wall structure Type of storage products Mechanism of motility Mode of replication Names are derived from major color displayed by group

4. Algal habitats Found in both fresh and salt water and soil Aquatic algae major producers of oxygen Also important users of carbon dioxide Algae often grow where other life forms can’t Often first to become established in barren environments Algae

5. Structure of algae Can be both micro and macroscopic Can float free or be propelled by flagella or filaments Macroscopic algae are multicellular Contain numerous structures for specific functions Holdfast anchors organism to firm substrate Stapes hold blades which are the major photosynthetic portion of algae Gas-containing bladders to help maintain blades in proper position for maximum sunlight Algae

6. Algae Structure of algae Cell wall Rigid structure made mostly of cellulose Diatoms have silicon dioxide incorporated in cell wall Cell structures Have membrane bound nucleus containing DNA Have both chloroplast and mitochondria Chloroplast for photosynthesis Mitochondria for respiration

7. Algae Algae reproduction Most single cell algae reproduce through binary fission Chromosome goes through mitosis Some algae reproduce through fragmentation Portion of parent organism breaks off to form new organism Sexual reproduction through meiosis also occurs

8. Algae Algae do not cause disease directly Numerous algae produce toxin Toxins are poisonous to humans Some species such as dinoflagellates produce neurotoxins Dinoflagellates eaten by shellfish and produce toxin Toxin accumulates in shellfish tissues Human eat shellfish and suffer paralytic shellfish poisoning

9. Protozoa Microscopic unicellular organisms Lack photosynthetic capability Usually motile Reproduce by asexual fission

10. Classification of protozoa Not a unified group Lumped together as unicellular organism lacking chlorophyll Traditionally divided into groups based on mode of locomotion Some belong to phylum Sarcomastigophora Includes two subphyla Mastigophora Sarcodina Protozoa

11. Protozoa Classification of protozoa Mastigophora Includes flagellated protozoa Most significant include Giardia lamblia, Leshmania species Trichomonas vaginalis and Trypanosoma species Sarcodina Move by means of pseudopodia Entamoeba hystolytica produces disease in humans

12. Classification of protozoa Other phylum include Ciliophora Organism have cilia Balantidium coli only pathogenic ciliate Apicomplexa Cause most serious protozoan disease Plasmodium species causes malaria Microspora Cause sever infection in immunocompromised Protozoa

13. Protozoa Protozoan habitats Majority are free-living Found in marine, fresh water and terrestrial habitats Essential decomposers Require large amounts of moisture Important part of food chain Protozoa eat bacteria and serve as food for larger species Help maintain ecological balance in soil Important in sewage disposal Results in decrease of sewage solids

14. Protozoa Structure of protozoa Cell wall Lack cell wall Shape determined by material beneath plasma membrane Cell structures Have membrane bound nucleus and organelles Lack photosynthetic chloroplasts Have specialized structures for movement Cilia, flagella or pseudopodia Protozoa grouped by mode of locomotion

15. Protozoa Protozoan reproduction Life cycles complex Often require more than one habitat or host Polymorphic Can exist as trophozoite or as cyst Both sexual and sexual reproduction common Many replicate via binary fission Many replicate by schizogony Many fissions Nucleus divides numerous times then cell produces numerous single celled organisms

16. Fungi Describes a taxonomic classification of organisms No longer includes slime molds and water molds Fungi require organic compounds for energy and as a carbon source Most are aerobic or facultative anaerobe Large number of fungi cause disease in plants Only a few cause disease in humans

17. Classification of fungi Can be both micro and macroscopic Cell wall consist of chitin No flagellated cells Four groups of true fungi Zygomycetes Basidiomycetes Ascomycetes Deuteroomycetes A.k.a fungi imperfecta Classification in groups based on sexual reproduction Except d where sexual reproduction is not seen Fungi

18. Classification of fungi Zygomycetes Includes common bread mold Rhizopus Ascomycetes Includes the fungi of Dutch elm disease Basidiomycetes Includes common mushroom and puffballs Deuteromycetes Includes medically and commercially important species including the penicillium Fungi

19. Fungi Classification of fungi Grouping of fungal forms Yeasts Single celled fungi Spherical, oval or cylindrical Reproduction through binary fission or budding Molds Filamentous fungi contain hyphae ? collection of hyphae called mycelium Reproductive spore is single celled ? germinates to develop hyphae ? cells divide into new form Dimorphic fungi Can grow as yeast or mold depending on environment Many pathogenic fungi are dimorphic

20. Fungi Fungal habitats Found in virtually every habitat Mainly terrestrial Fungal spores found throughout the earth Uncountable numbers found in air Major cause of asthma Growth requirements of fungi Slightly moist environment with high humidity 70% or higher pH range varies Most grow well in slightly acidic environment Most are aerobic Some yeast facultative Some fungi obligate anaerobes

21. Fungi Fungal diseases in humans Cause disease in one of four ways Allergic reaction Result from inhaling fungal spores React to fungal toxin Many have hallucinogenic properties Certain species produces alflatoxin implicated in cancer Mycoses Fungi grows on or in the body Economic impact Destroy human food supply causing starvation

22. Fungi Symbiotic relationships of fungi Form several symbiotic relationships with other organisms Lichens result from relationship between fungi and photosynthetic organism Relationships are very close Fungus provides protection and growing platform Other organism supplies nutrient Mycorrhizae symbiosis with roots of plants Increases absorptive property of roots Allow plant partners to grow in dryer climates

23. Fungi Economic importance of fungi Many are important commercially Saccharomyces used in production of beer, wine and bread Many important for cheese production Penicillin, griseofulvin as well as other antimicrobials are made from fungi Elimination of disease causing fungi from commercial crops vitally important Fungi used in genetic and biochemical studies Yeast genetically engineered to produce human insulin

24. Slime Molds and Water Molds Used to be considered types of fungi They are completely unrelated Good example of convergent evolution Two organisms develop similar characteristics and adaptations but not related on molecular level

25. Slime Molds and Water Molds Acellular slime molds Terrestrial organisms Non motile Reproduction depends of formation of dispersible spores Acellular slime molds readily visible in environment Plasmodium formed from nucleus spreads over surface of decaying matter Cellular slime molds Has vegetative form made of ameba-like cells Single cells congregate into form called slug Slug forms fruiting body and spores

26. Slime Molds and Water Molds Water molds A.k.a Oomycetes Members of heterokonts Do not have chlorophyll Once considered fungi Due to morphology Form masses of white thread on decaying matter Zoospores cause serious disease of food crops

27. Multicellular Parasites: Arthropods and Helminths Arthropods include Insects such as mosquitoes responsible for transmission of malaria and fleas which transmits plague Ticks responsible for transmission of Rocky Mountain Spotted Fever and Lyme disease Lice responsible for transmission of typhus and other fevers Mites transmit scabies Helminths include nematodes, cestodes and tremetodes Cause disease by invading host tissues and robbing nutrients Nematodes invade gastrointestinal tract and blood stream Cestodes associated with meats especially pork Transmission results from consumption of uncooked meat Trematodes Can be found discharged in waters such as lakes and ponds

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