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Eukaryotic Cells and Microorganisms.


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Eukaryotic Cells and Microorganisms.

  1. 1. Foundations in Microbiology Chapter 5 PowerPoint to accompany Fifth Edition Talaro Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  2. 2. Eucaryotic cells and microorganisms Chapter 5
  3. 3. 3 Eucaryotic cells
  4. 4. Flagella <ul><li>long, sheathed cylinder containing microtubules in a 9+2 arrangement </li></ul><ul><li>covered by an extension of the cell membrane </li></ul><ul><li>10X thicker than procaryotic flagella </li></ul><ul><li>function in motility </li></ul>
  5. 5. Flagella
  6. 6. Cilia <ul><li>similar in overall structure to flagella, but shorter and more numerous </li></ul><ul><li>found only on a single group of protozoa and certain animal cells </li></ul><ul><li>function in motility, feeding & filtering </li></ul>
  7. 7. Glycocalyx <ul><li>an outermost boundary that comes into direct contact with environment </li></ul><ul><li>usually composed of polysaccharides </li></ul><ul><li>appears as a network of fibers, a slime layer or a capsule </li></ul><ul><li>functions in adherence, protection, & signal reception </li></ul><ul><li>beneath the glycocalyx </li></ul><ul><ul><li>fungi and most algae have a thick, rigid cell wall </li></ul></ul><ul><ul><li>protozoa, a few algae, and all animal cells lack a cell wall & have only a membrane </li></ul></ul>
  8. 8. Glycocalyx structure
  9. 9. Cell wall <ul><li>rigid & provide structural support & shape </li></ul><ul><li>fungi have thick inner layer of polysaccharide fibers composed of chitin or cellulose & a thin layer of mixed glycans </li></ul><ul><li>Algae – varies in chemical composition; substances commonly found include cellulose, pectin, mannans, silicon dioxide, & calcium carbonate </li></ul>
  10. 10. Cell membrane <ul><li>typical bilayer of phospholipids and proteins </li></ul><ul><li>sterols confer stability </li></ul><ul><li>serve as selectively permeable barriers in transport </li></ul><ul><li>eucaryotic cells also contain membrane-bound organelles that account for 60-80% of their volume </li></ul>
  11. 11. nucleus <ul><li>compact sphere, most prominent organelle of eucaryotic cell </li></ul><ul><li>nuclear envelope is composed of two parallel membranes separated by a narrow space & is perforated with pores </li></ul><ul><li>contains chromosomes </li></ul><ul><li>nucleolus – dark area for rRNA synthesis & ribosome assembly </li></ul>
  12. 12. nucleus
  13. 13. Mitosis
  14. 14. Endoplasmic reticulum <ul><li>Rough endoplasmic reticulum (RER)– originates from the outer membrane of the nuclear envelop & extends in a continuous network through cytoplasm; rough due to ribosomes, proteins are synthesized & shunted into the ER for packaging & transport. First step in secretory pathway. </li></ul><ul><li>Smooth endoplasmic reticulum (SER)– closed tubular network without ribosomes, functions in nutrient processing, synthesis & storage of lipids, etc. </li></ul>
  15. 15. rough endoplasmic reticulum (RER)
  16. 16. Golgi apparatus <ul><li>consists of a stack of flattened sacs called cisternae </li></ul><ul><li>closely associated with ER </li></ul><ul><li>Transistional vesicles from the ER containing proteins go to the Golgi apparatus for modification and maturation </li></ul><ul><li>Condensing vesicles transport proteins to organelles or secretory proteins to the outside </li></ul>
  17. 17. Golgi apparatus
  18. 18. Transport process
  19. 19. lysosomes <ul><li>vesicles containing enzymes </li></ul><ul><li>involved in intracellular digestion of food particles & in protection against invading microbes </li></ul>
  20. 20. lysosomes
  21. 21. mitochondria <ul><li>consists of an outer membrane & an inner membrane with folds called cristae </li></ul><ul><li>cristae hold the enzymes & electron carriers of areobic respiration </li></ul><ul><li>divide independently of cell </li></ul><ul><li>contain DNA and procaryotic ribosomes </li></ul><ul><li>function in energy production </li></ul>
  22. 22. mitochondria
  23. 23. chloroplast <ul><li>found in algae & plant cells </li></ul><ul><li>outer membrane covers inner membrane folded into sacs, thylakoids, stacked into grana </li></ul><ul><li>larger than mitochondria </li></ul><ul><li>contain photosynthetic pigments </li></ul><ul><li>convert the energy of sunlight into chemical energy through photosynthesis </li></ul><ul><li>primary producers of organic nutrients for other organisms </li></ul>
  24. 24. chloroplast
  25. 25. cytoskeleton <ul><li>flexible framework of proteins, microfilaments & microtubules form network throughout cytoplasm </li></ul><ul><li>involved in movement of cytoplasm, ameboid movement, transport, & structural support </li></ul>
  26. 26. cytoskeleton
  27. 27. ribosomes <ul><li>composed of rRNA and proteins </li></ul><ul><li>40S and 60S subunits form 80S ribosomes </li></ul><ul><li>larger than procaryotic ribosomes </li></ul><ul><li>function in protein synthesis </li></ul>
  28. 28. Survey of eucaryotic microbes <ul><li>Fungi </li></ul><ul><li>Algae </li></ul><ul><li>Protozoa </li></ul><ul><li>Parasitic helminths </li></ul>
  29. 29. Kingdom Fungi <ul><li>100,000 species divided into 2 groups: </li></ul><ul><ul><li>macroscopic fungi ( mushrooms, puffballs, gill fungi) </li></ul></ul><ul><ul><li>microscopic fungi (molds, yeasts) </li></ul></ul><ul><li>majority are unicellular or colonial, a few have cellular specialization </li></ul>
  30. 30. microscopic fungi <ul><li>exist in 2 morphologies </li></ul><ul><ul><li>yeast – round ovoid shape, asexual reproduction </li></ul></ul><ul><ul><li>hyphae – long filamentous fungi or molds </li></ul></ul><ul><li>some exist in either form – dimorphic – characteristic of pathogens </li></ul>
  31. 31. Morphology of yeasts
  32. 32. Hyphae or mold
  33. 33. Fungal nutrition <ul><li>all are heterotrophic </li></ul><ul><li>majority are harmless saprobes living off dead plants & animals </li></ul><ul><li>some are parasites, living on the tissues of other organisms, but none are obligate; mycoses – fungal infections </li></ul><ul><li>growth temperature 20 o -40 o C </li></ul><ul><li>extremely widespread distribution in many habitats </li></ul>
  34. 34. Fungal Reproduction <ul><li>primarily through spores formed on special reproductive hyphae </li></ul><ul><ul><li>asexual reproduction – spores are formed through budding or in conidia or sporangiospores </li></ul></ul><ul><ul><li>sexual reproduction – spores are formed following fusion of male & female strains & formation of sexual structure </li></ul></ul><ul><li>sexual spores are one basis for classification </li></ul>
  35. 35. Asexual mold spores
  36. 36. 4 main divisions based on spore type <ul><li>Zygomycota </li></ul><ul><li>Ascomycota </li></ul><ul><li>Basidiomycota </li></ul><ul><li>Deuteromycota – no sexual spores </li></ul>
  37. 37. I. Zygospores
  38. 38. II. Ascospores
  39. 39. III. Basidospores
  40. 40. Roles of fungi <ul><li>decomposers of dead plants and animals </li></ul><ul><li>sources of antibiotics </li></ul><ul><li>used in making foods & in genetic studies </li></ul><ul><li>adverse impact – food spoilage, mycoses, toxin production </li></ul>
  41. 41. Kingdom Protista <ul><li>algae </li></ul><ul><li>protozoa </li></ul>
  42. 42. Algae <ul><li>photosynthetic organisms </li></ul><ul><li>kelps, seaweeds, euglenids, green algae, diatoms, dinoflagellates, brown algae, & red seaweeds </li></ul><ul><li>contain chloroplasts with chlorophyll & other pigments; cell wall; may or may not have flagella </li></ul><ul><li>microscopic forms are unicellular, colonial, filamentous </li></ul><ul><li>macroscopic forms are colonial and multicellular </li></ul><ul><li>most are free-living in fresh and marine water </li></ul>
  43. 43. Algae
  44. 44. Algae <ul><li>classified according to types of pigments & cell wall </li></ul><ul><li>provide basis of food web in most aquatic habitats </li></ul><ul><li>produce large proportion of atmospheric O2 </li></ul><ul><li>used for cosmetics, food & medical products </li></ul><ul><li>Dinoflagellates cause red tides & give off toxins </li></ul>
  45. 45. Protozoa <ul><li>65,000 species </li></ul><ul><li>most are unicellular, colonies are rare </li></ul><ul><li>most have locomoter structures – flagella, cilia, or pseudopods </li></ul><ul><li>vary in shape </li></ul><ul><li>lack a cell wall & chloroplasts </li></ul><ul><li>can exist in trophozoite - motile feeding stage or cyst – a dormant resistant stage </li></ul>
  46. 46. Protozoa
  47. 47. Protozoa <ul><li>all are heterotrophic, </li></ul><ul><li>most are free-living in a moist habitat </li></ul><ul><li>feed by engulfing other microbes & organic matter </li></ul><ul><li>some are animal parasites & can be spread by insect vectors </li></ul><ul><li>asexual and sexual reproduction </li></ul>
  48. 48. Groups based on locomotion & reproduction <ul><li>Mastigophora – flagellates </li></ul><ul><li>Sarcodina – amebas </li></ul><ul><li>Ciliophora – ciliates </li></ul><ul><li>Apicomplexa – all parasites motility not well developed; produce unique reproductive structures </li></ul>
  49. 49. Mastigophora – flagellates
  50. 50. Sarcodina – amebas
  51. 51. Ciliophora – ciliates
  52. 52. Apicomplexa
  53. 53. Parasitic Helminths <ul><li>multicellular animals, organs for reproduction, digestion, movement, protection </li></ul><ul><li>parasitize host tissues </li></ul><ul><li>have mouthparts for attachment to or digestion of host tissues </li></ul><ul><li>most have well-developed sex organs that produce eggs and sperm. </li></ul><ul><li>fertilized eggs go through larval period in or out of host body </li></ul>
  54. 54. Major groups of helminths <ul><li>flatworms – flat, no definite body cavity; digestive tract a blind pouch; simple excretory & nervous systems </li></ul><ul><ul><li>cestodes (tapeworms) </li></ul></ul><ul><ul><li>trematodes or flukes, are flattened , nonsegmented worms with sucking mouthparts </li></ul></ul><ul><li>roundworms (nematodes)- round, a complete digestive tract, a protective surface cuticle, spines & hooks on mouth; excretory & nervous systems poorly developed </li></ul>
  55. 55. Helminths <ul><li>50 species parasitize humans </li></ul><ul><li>acquired though ingestion of larvae or eggs in food; from soil or water; some are carried by insect vectors </li></ul><ul><li>afflict billions of humans </li></ul>