Chapter 27 - CR

Chapter 27 - CR - Chapter 27 Chapter 27 Prokaryotes Theyre...

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Unformatted text preview: Chapter 27 Chapter 27 Prokaryotes Theyre (Almost) Everywhere! Theyre (Almost) Everywhere! Most prokaryotes are microscopic The number of prokaryotes in a single handful of fertile soil is greater than the number of people who have ever lived Prokaryotes thrive almost everywhere Including places too acidic, too salty, too cold, or too hot for most other organisms Biologists are discovering that these organisms have an astonishing genetic diversity Many adaptations contribute to Many adaptations contribute to prokaryotic success prokaryotic success Most prokaryotes are unicellular, although some species form colonies The three most common shapes are spheres (cocci ), rods (bacilli ), and spirals Nearly all prokaryotic cells have a cell wall It maintains cell shape, provides physical protection, and prevents the cell from bursting in a hypotonic environment The Gram stain is used to classify many bacterial species into two groups based on cell wall composition, Gram-positive and Gram-negative High amount of peptidoglycan stains dark The cell wall of many prokaryotes is covered by a capsule, a sticky layer of polysaccharide or protein Some prokaryotes have fimbriae and pili , which allow them to stick to their substrate or other individuals in a colony 200 nm Capsule Figure 27.4 200 nm Fimbriae Motility Most motile bacteria propel themselves by flagella which are s tructurally and functionally different from eukaryotic flagella Many bacteria exhibit taxis...
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This note was uploaded on 04/07/2008 for the course BIO 103 taught by Professor Mannino during the Fall '08 term at Long Island U..

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Chapter 27 - CR - Chapter 27 Chapter 27 Prokaryotes Theyre...

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