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UNIT 3

UNIT 3. THE MICROBIAL WORLD. PROKARYOTES. Single-celled Oldest forms of life on earth Have cell wall Plasma/cell membrane NO nucleus and other membrane bound organelles Circular DNA Two prokaryotic domains: Bacteria and Archae. BACTERIA. 3 basic shapes: Cocci = round Bacilli= rod

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UNIT 3

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  1. UNIT 3 THE MICROBIAL WORLD

  2. PROKARYOTES • Single-celled • Oldest forms of life on earth • Have cell wall • Plasma/cell membrane • NO nucleus and other membrane bound organelles • Circular DNA • Two prokaryotic domains: Bacteria and Archae

  3. BACTERIA • 3 basic shapes: • Cocci = round • Bacilli= rod • Spirilli =spiral • There is also a fourth shape- rings but not as common

  4. Coccus Bacillus

  5. Spirillum

  6. Pelagibacter ubique - the most abundant life form on the planet - just recently discovered -found in open water

  7. SYMBIOTIC BACTERIA • Bacteria that live in close association with other marine organisms

  8. BIOLUMINESCENT BACTERIA • Bacteria that cause the light produced by some fish, squids, octopuses, and other animals of the deep- symbiotic relationship • Bacteria is sheltered in light-producing organs called PHOTOPHORES • Use the light to communicate, attract prey • Video 1 • Video 2

  9. Chemosynthetic Bacteria • Symbiotic with mussels, clams, and tubeworms • Around hydrothermal vents • Manufacture organic matter from CO2 and the hydrogen sulfide from the vents • Live in the “feeding body” of the giant hydrothermal-vent tube worm Riftia

  10. Riftia

  11. TETRODOTOXIN • Some symbiotic bacteria affect human health- such as the neurotoxin (tetrodotoxin) produced by symbiotic bacteria in pufferfish • One of the most powerful poisons, no anecdote • Found in the liver and gonads of the fish

  12. Porcupine pufferfish

  13. Tetrodotoxin and other similar toxins are also found in flatworms, snails, crabs, sea stars and several species of fish • Also found in the blue-ringed octopus- very toxic animal

  14. CYANOBACTERIA • “Blue-green” algae; photosynthetic • Contain chlorphyll a and a bluish pigment called PHYCOCYANIN • Most marine cyanobacteria also have a reddish pigment called PHYCOERYTHRIN • One of the first photosynthetic organisms on earth • Important in O2 production

  15. STROMATOLITES- fossil calcareous mounds formed by cyanobacteria- 3 billion years old; still being formed

  16. Cyanobacteria can tolerate wide ranges of salinity and temperature- • Endolithic= go into calcareous rocks and coral skeletons; form thick dark crusts on shoreline • Planktonic= multiply fast; change the color of the water • Epiphytes= photosynthetic bacteria that love on algae or plants • Endophytes= bacteria that live in algae

  17. ARCHAE video • Simplest and primitive form of life • Important in the early evolution of life • Small and can by any of the three shapes of bacteria • MORE CLOSELY RELATED TO EUKARYOTES THAN BACTERIA • Can tolerate extreme environments- known as extremophiles but are not only found in these environments • Common in water and sediment environments

  18. PROKARYOTIC METABOLISM • METABOLISM= all the chemical reactions that takes place in an organism • AUTOTROPHIC = make their own food; primary producers • Photoautotrophic= have chlorophyll or other pigments that capture sunlight and transfer it into organic compounds • Occurs in the bacterial membrane

  19. CHEMOSYNTHETIC OR CHEMOAUTOTROPHIC= derive energy from other chemicals like hydrogen sulfide or other sulfur, nitrogen and iron compounds • Methanogens= produce methane (CH4)

  20. HETEROTROPHS • Most marine bacteria • Cannot produce own food; obtain energy from respiration • Many are decomposers • Aerobic bacteria use oxygen; anaerobic bacteria do not require oxygen for respiration (thrive only when oxygen is not present)

  21. some bottom-dwelling and planktonic cyanobacteria undergo nitrogen fixation where they convert nitrogen into ammonium which can be used a a source of nitrogen by primary producers

  22. UNICELLULAR ALGAE • Mostly photosynthetic; have chloroplasts; eukaryotic • Lack flowers; have very simple reproductive structures; lack true leaves, stems and roots • Some show animal-like characteristics; move with a flagella; some consume food • considered protists

  23. Chlorella sp

  24. DIATOMS • PHYLUM- Heterokontophyta c • CLASS- Bacillarophyta • Unicellular • Cell walls made up of silicon (SiO2); this glass shell is known as a frastule • made up of two tightly fitted halves- looks like a box; different shapes • May have spines or ribs • Allows light to pass through so that the golden-brown chloroplasts can capture light • The perforations allow dissolved gases and nutrients to enter and exit

  25. diatoms

  26. Diatoms cont… • Color caused by yellow and brown carotenoid pigments • Also has chlorophyll a and c • 12,000 species (half of these marine) • Most planktonic, but some have a stalk-like structure for attachment • Reproduce asexually by cell division • Frustules get progressively smaller

  27. Diatom cont….. • Can also reproduce sexually • Resistant stages called auxospores- are larger diatoms; can be formed either asexually or through sexual reproduction • Rapid reproduction known as blooms • Deposits of frustules of dead diatoms forms a biogenous sediment of siliceaous material on the ocean floor; also known as diatomaceous ooze- forms diatomaceous earth which is used for filters in pools, for clarifying beer, as temp and sound insulators

  28. DINOFLAGELLATES • Unicellular organisms • 2 flagella; one wrapped around a groove in the middle of the cell and one free • Cell wall made of “plates” of cellulose • Autotrophic and heterotrophic • All marine • Reproduce by cell division • Blooms form “Red Tides” • Some bioluminescent

  29. Zooanthellae- dinoflagellate that are round, golden-brown • Live in close assoc. with some animals such as sponges, and sea anenomes • Important in reef corals because they fix carbon dioxide via photosynthesis and help build the coral skeleton (mine does not have the zooanthellae and that is why I need to supplement feed it shrimp)

  30. Some dinoflagellates have life cycles with cyst stages and free-swimming larval stages • Pfiesteria- or the “phantom dinoflagellate” exists mostly as a cyst • Responsible for open sores on fish

  31. Other Unicellular Algae • Silicoflagellates- star-shaped internal skeleton of silica; 2 flagella; common in marine sediments • Coccolithophorids- flagellated, spherical cells covered with button like structures called coccoliths made of calcium carbonate; found in sediments as fossils

  32. PROTOZOANS- ANIMAL LIKE PROTISTS • Eukaryotic • Single-celled; some form colonies • Heterotrophic

  33. Foraminiferans • Forams; have a shell or test made of calcium carbonate • Have pseudopodia (extensions of the cytoplasm); used for movement and obtaining of food • Live on bottom; free or attached • White Cliffs of Dover produced by foram sediments

  34. RADIOLARIANS • Planktonic- in open water • Secrete shells made of glass (silica) • Usually spherical with spines • Pseudopodia captures food

  35. Ciliates • Have cilia for locomotion and feeding • Paramecium • May be free living, attached to surfaces or within other organisms • Important food source

  36. Fungi • Multicellular or unicellular (molds and yeasts) • 500 marine species • Decompose detritus • Some parasitic • Marine lichens

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