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Eukaryotic cells-and-microorganisms884
- 1. Foundations in Microbiology Chapter 5 PowerPoint to accompany Fifth Edition Talaro Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
- 4. 4 Flagella • long, sheathed cylinder containing microtubules in a 9+2 arrangement • covered by an extension of the cell membrane • 10X thicker than procaryotic flagella • function in motility
- 5. 5 Flagella
- 6. 6 Cilia • similar in overall structure to flagella, but shorter and more numerous • found only on a single group of protozoa and certain animal cells • function in motility, feeding & filtering
- 7. 7 Glycocalyx • an outermost boundary that comes into direct contact with environment • usually composed of polysaccharides • appears as a network of fibers, a slime layer or a capsule • functions in adherence, protection, & signal reception • beneath the glycocalyx – fungi and most algae have a thick, rigid cell wall – protozoa, a few algae, and all animal cells lack a cell wall & have only a membrane
- 9. 9 Cell wall • rigid & provide structural support & shape • fungi have thick inner layer of polysaccharide fibers composed of chitin or cellulose & a thin layer of mixed glycans • Algae – varies in chemical composition; substances commonly found include cellulose, pectin, mannans, silicon dioxide, & calcium carbonate
- 10. 10 Cell membrane • typical bilayer of phospholipids and proteins • sterols confer stability • serve as selectively permeable barriers in transport • eucaryotic cells also contain membrane- bound organelles that account for 60-80% of their volume
- 11. 11 nucleus • compact sphere, most prominent organelle of eucaryotic cell • nuclear envelope is composed of two parallel membranes separated by a narrow space & is perforated with pores • contains chromosomes • nucleolus – dark area for rRNA synthesis & ribosome assembly
- 12. 12 nucleus
- 13. 13 Mitosis
- 14. 14 Endoplasmic reticulum • 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. • Smooth endoplasmic reticulum (SER)– closed tubular network without ribosomes, functions in nutrient processing, synthesis & storage of lipids, etc.
- 16. 16 Golgi apparatus • consists of a stack of flattened sacs called cisternae • closely associated with ER • Transistional vesicles from the ER containing proteins go to the Golgi apparatus for modification and maturation • Condensing vesicles transport proteins to organelles or secretory proteins to the outside
- 19. 19 lysosomes • vesicles containing enzymes • involved in intracellular digestion of food particles & in protection against invading microbes
- 20. 20 lysosomes
- 21. 21 mitochondria • consists of an outer membrane & an inner membrane with folds called cristae • cristae hold the enzymes & electron carriers of areobic respiration • divide independently of cell • contain DNA and procaryotic ribosomes • function in energy production
- 22. 22 mitochondria
- 23. 23 chloroplast • found in algae & plant cells • outer membrane covers inner membrane folded into sacs, thylakoids, stacked into grana • larger than mitochondria • contain photosynthetic pigments • convert the energy of sunlight into chemical energy through photosynthesis • primary producers of organic nutrients for other organisms
- 24. 24 chloroplast
- 25. 25 cytoskeleton • flexible framework of proteins, microfilaments & microtubules form network throughout cytoplasm • involved in movement of cytoplasm, ameboid movement, transport, & structural support
- 26. 26 cytoskeleton
- 27. 27 ribosomes • composed of rRNA and proteins • 40S and 60S subunits form 80S ribosomes • larger than procaryotic ribosomes • function in protein synthesis
- 28. 28 Survey of eucaryotic microbes • Fungi • Algae • Protozoa • Parasitic helminths
- 29. 29 Kingdom Fungi • 100,000 species divided into 2 groups: – macroscopic fungi ( mushrooms, puffballs, gill fungi) – microscopic fungi (molds, yeasts) • majority are unicellular or colonial, a few have cellular specialization
- 30. 30 microscopic fungi • exist in 2 morphologies – yeast – round ovoid shape, asexual reproduction – hyphae – long filamentous fungi or molds • some exist in either form – dimorphic – characteristic of pathogens
- 33. 33 Fungal nutrition • all are heterotrophic • majority are harmless saprobes living off dead plants & animals • some are parasites, living on the tissues of other organisms, but none are obligate; mycoses – fungal infections • growth temperature 20o -40o C • extremely widespread distribution in many habitats
- 34. 34 Fungal Reproduction • primarily through spores formed on special reproductive hyphae – asexual reproduction – spores are formed through budding or in conidia or sporangiospores – sexual reproduction – spores are formed following fusion of male & female strains & formation of sexual structure • sexual spores are one basis for classification
- 36. 36 4 main divisions based on spore type 1. Zygomycota 2. Ascomycota 3. Basidiomycota 4. Deuteromycota – no sexual spores
- 37. 37 I. Zygospores
- 40. 40 Roles of fungi • decomposers of dead plants and animals • sources of antibiotics • used in making foods & in genetic studies • adverse impact – food spoilage, mycoses, toxin production
- 41. 41 Kingdom Protista • algae • protozoa
- 42. 42 Algae • photosynthetic organisms • kelps, seaweeds, euglenids, green algae, diatoms, dinoflagellates, brown algae, & red seaweeds • contain chloroplasts with chlorophyll & other pigments; cell wall; may or may not have flagella • microscopic forms are unicellular, colonial, filamentous • macroscopic forms are colonial and multicellular • most are free-living in fresh and marine water
- 43. 43 Algae
- 44. 44 Algae • classified according to types of pigments & cell wall • provide basis of food web in most aquatic habitats • produce large proportion of atmospheric O2 • used for cosmetics, food & medical products • Dinoflagellates cause red tides & give off toxins
- 45. 45 Protozoa • 65,000 species • most are unicellular, colonies are rare • most have locomoter structures – flagella, cilia, or pseudopods • vary in shape • lack a cell wall & chloroplasts • can exist in trophozoite- motile feeding stage or cyst – a dormant resistant stage
- 46. 46 Protozoa
- 47. 47 Protozoa • all are heterotrophic, • most are free-living in a moist habitat • feed by engulfing other microbes & organic matter • some are animal parasites & can be spread by insect vectors • asexual and sexual reproduction
- 48. 48 Groups based on locomotion & reproduction • Mastigophora – flagellates • Sarcodina – amebas • Ciliophora – ciliates • Apicomplexa – all parasites motility not well developed; produce unique reproductive structures
- 52. 52 Apicomplexa
- 53. 53 Parasitic Helminths • multicellular animals, organs for reproduction, digestion, movement, protection • parasitize host tissues • have mouthparts for attachment to or digestion of host tissues • most have well-developed sex organs that produce eggs and sperm. • fertilized eggs go through larval period in or out of host body
- 54. 54 Major groups of helminths 1. flatworms – flat, no definite body cavity; digestive tract a blind pouch; simple excretory & nervous systems • cestodes (tapeworms) • trematodes or flukes, are flattened , nonsegmented worms with sucking mouthparts 1. roundworms (nematodes)- round, a complete digestive tract, a protective surface cuticle, spines & hooks on mouth; excretory & nervous systems poorly developed
- 55. 55 Helminths • 50 species parasitize humans • acquired though ingestion of larvae or eggs in food; from soil or water; some are carried by insect vectors • afflict billions of humans
- 56. 56
- 57. 57
- 58. 58
- 59. 59