12-ch16-microbes - Chapter 16 continued Chapter 16...

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Unformatted text preview: Chapter 16 continued: Chapter 16 continued: Microbes Microbes Early microbiologists http://www.learner.org/vod/vod_window.html?pid=1363 w o d h — Hilaire Belloc, 1900 The Microbe is so very small You cannot make him out at all, But many sanguine people hope To see him through a microscope. “micro” = small “bios” = life They’re They’re (almost) everywhere! prokaryotes include two whole domains: archaea, bacteria significant ecological roles include... decomposition – converts organic compounds to CO2 gas; needed for photosynthesis nitrogen fixation – convert N2 gas to nitrates, nitrites (in soil); needed for plants to make amino acids denitrification – (reverse of above); release atmospheric N2 pathogens... e.g., cholera, tuberculosis, gonorrhea, anthrax, lyme disease, rocky mountain spotted fever, scarlet fever, typhoid fever, tetanus, cat scratch fever, pneumonia, meningitis, leprosy, food poisoning (salmonellosus botulism etc urinary tract infections toothache (salmonellosus, botulism, etc.), urinary tract infections, toothache Bacteria Bacteria come in three general shapes • unicellular, 1-5 micrometers • cell wall bacilli • no organelles (compartmentalization) cocci • spheres, rods, & spirals spirilla & spirochetes • asexual reproduction via binary fission (mitosis) but have methods for occasional transfer of genetic material The The amazing reproductive potential of binary fission Some species can produce a new generation in only 20 minutes under optimal conditions. If reproduction continued unchecked at this rate, a single prokaryote could give rise to a colony hi outweighing Earth in only three days! In reality, of course, prokaryotic reproduction is limited, as the li cells eventually exhaust their nutrient supply, poison themselves with metabolic wastes, or are consumed by other organisms... (Campbell & Reece 7th ed.) Some prokaryotes can withstand unfavorable conditions… endospore – thick-coated, resistant cell produced within a bacterial cell exposed to harsh conditions e.g., lack of moisture, nutrient shortage live (dormant) for centuries until conditions improve hard to kill (survive boiling water!) Bacillus anthracis (endospore) Nutritional Nutritional adaptations Every type of nutrition observed in eukaryotes is represented among Every type of nutrition observed in eukaryotes is represented among prokaryotes, prokaryotes, along with some unique nutritional modes. (C&R 7th ed) biofilm – surface-coating colony (or community) of prokaryotes biofilm surfacethat engage in metabolic cooperation http://nai.nasa.gov/team/customtags/projectreports.cfm?teamID=49&year=9&projectID=1977 http://toxics.usgs.gov/photo_gallery/metals_variation.html extracellular protein matrix anchors colony; channels allow transport of nutrients, waste dirty dishwater plaque on teeth on teeth sinus infection aquarium filters filters stromatolite fossils quorum quorum sensing: see bacteria in a whole new light! But first… what do a bluefin tuna, a sandbar shark, and a leopard frog have in common with many other swimmers? Bonnie Brassler on how bacteria “talk” http://www.ted.com/index.php/talks/bonnie_bassler_on_how_bacteria_communicate.html Satellite Spots 'Glowing' Ocean http://www.npr.org/templates/story/story.php?storyId=4990705 Archaea “the ancient ones” Archaea extremophile – lives in extreme environment (energetic investment in specialized adaptations) extreme thermophile – thrive in hot conditions (recall Taq) extreme halophile – thrive in high salinity conditions halophile in high salinity conditions methanogen – microorganism that obtains energy by using carbon dioxide to oxidize hydrogen; makes methane waste carbon dioxide to oxidize hydrogen; makes methane waste - obligate anaerobes; produce “marsh gas” & cow farts - recycle water in sewage treatment ponds; bioremediation water in sewage treatment ponds; bioremediation Archaea are not the only extremophiles (e.g., acidophilic bacteria thrive in gastric juices at pH 2) bacteria thrive in gastric juices at pH 2)... “thermo” = hot “halo” = salt “phile” = lover Pathogenic Pathogenic effects exotoxins – toxic protein secreted by bacterial cell; produces specific symptoms even in the absence of the bacterium Vibrio cholerae toxin stimulates intestinal cells to release chloride, upsetting water balance (diarrhea, dehydration) Clostridium botulinum secretes a nerve toxin endotoxins – component of outer membrane (certain gramnegative bacteria) responsible for fever, ache symptoms Salmonella baby turtle fad “exo” = outside “endo” = inside Not Not all microbes are prokaryotes! “Oh gawd – here comes Lenny with something he picked up off the toilet seat!” Protists are a diverse assortment of eukaryotes protist – any eukaryote that is not plant, fungus, or animal eukaryote that is not plant fungus or animal (motley assortment formerly known as a kingdom) structurally & functionally diverse di • most are unicellular (some colonial, some multicellular) • most are aquatic • autotrophs, heterotrophs & mixotrophs (both) heterotrophs mixotrophs • some free-living, some symbionts (of all three types) • some sit still, some float passively, some swim sit still some float passively some swim • asexual reproduction, sexual reproduction, or both “Protist” “Protist” is a catch-all category for eukaryote misfits catch- Alveolates Stramenopila Amoebozoa ** ** * most eukaryotic lineages are protists (marked ) * ancestral eukaryote ancestral eukaryote * *** some “protists” are more closely related to animals (& fungi) or plants than to other “protists” Protists Protists are a diverse assortment of eukaryotes ecologically diverse diverse algae protozoans .................... photosynthetic, plant-like protists ingestive, animal-like protists absorptive fungus-like protists plankton – aquatic organisms too small to control aquatic organisms too small to control their their own horizontal movement (vs. nekton) nekton phytoplankton = autotrophic zooplankton = heterotrophic heterotrophic Euglenozoans Euglenozoans are protozoa with flagella many euglenids make some of their own food via photosynthesis euglenids make some of their own food via photosynthesis Euglenozoans Euglenozoans include the parasite Trypanosoma which causes sleeping sleeping sickness & Chagas disease Chagas Alveolates include dinoflagellates (abundant phytoplankton) - red tides tid - shellfish poisoning Alveolates include dinoflagellates Alveolates dinoflagellates (abundant (abundant phytoplankton) - bioluminescence - bioindicator Vieques' Growth Threatens Bioluminescent Bay http://www.npr.org/templates/story/story.php?storyId=91303971 Pyrocystis fusiformis u s shaken in plastic bag a http://www.audubonmagazine.org/features0611/destinations.html Another Alveolate is Plasmodium, the parasitic Another Alveolate Plasmodium protozoan that causes malaria http://www.npr.org/programs/atc/features/2008/feb/potato/slideshow/index.html Stramenopiles Stramenopiles include the “water mold” called late blight “water late from the Irish Potato Famine from the Irish Potato Famine (1845(1845-1849) to contemporary highland Peru... Soup without potatoes is Soup without potatoes is like like life without love — Peruvian proverb Stramenopiles Stramenopiles include diatoms; phytoplankton diatoms (algae) with intricate glass walls nanotech skin care aquarium filters some Amoebozoans are free-living; others are parasitic some Amoebozoans freeEntamoebas are parasitic; dysentery parasitic; dysentery Gymnamoebas are free-living Amoebozoans Amoebozoans also include slime molds slime Slime “molds” live in moist moist organic debris they are heterotrophs who prey on bacteria, yeast, yeast, algae, etc. Stramenopiles Stramenopiles include golden & brown algae Golden algae are components of freshwater & marine plankton Brown algae are large, multicellular marine organisms (seaweed) Red algae & green algae are the closest Red green relatives of land plants Watermelon Snow Red algae & green algae are the closest relatives of plants Red green ...
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