Proteins in the envelope are virus specic and are

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Unformatted text preview: – are highly differenAated cells that are extremely resistant to harsh environmental condiAons: heat, chemicals, radiaAon, nutrient depleAon, desiccaAon, etc. The endospore is a dormant stage in the life cycle and is easily dispersed by wind, water, animal digesAve system, etc. Endospores can remain dormant for 100s of years. •  Best studied in Clostridium species and Bacillus species (Gram- posiAve). 64 Brock Biology of Microorganisms, 13th EdiAon. ComposiAon of the endospore •  Exosporium: proteins. •  Spore coat: layers of spore- specific proteins (keraAn- like). •  Cortex: pepAdoglycan. •  Core (cytoplasm): Ca2+, dipicolinic acid (DPA), SASPs (small, acid soluble spore proteins). •  SASPs bind to DNA and help protect it. •  DPA and Ca2+ bind water, dehydrate the core. •  The core also contains proteins needed for germinaAon. DPA 65 Brock Biology of Microorganisms, 13th EdiAon. FormaAon of the endospore 66 Brock Biology of Microorganisms, 13th EdiAon. GerminaAon AcAvaAon Spore Outgrowth GerminaAon Outgrowth 67 Cell inclusions •  In prokaryoAc cells, energy reserves and building blocks are someAmes stored in granules or inclusions. •  In some cases, the cell inclusions can be enclosed by a single layer membrane (phospholipid, protein, glycoprotein). •  Storage of nutrients: –  Carbon –  Sulfur –  Polyphosphate •  Magnetosome contains magneAte (Fe3O4) and allows the bacteria to respond to magneAc fields (magnetotaxis). 68 Brock Biology of Microorganisms, 13th EdiAon. InfecAous parAcles Chap. 9 Viruses, viroids, prions 69 Viruses •  Viruses are obligate intracellular parasites, they can replicate only inside host cells. •  Host cells of viruses include all groups of cellular organisms (b...
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