notes 2 - Chapter 27: Prokaryotes Concept 27.1: Structural...

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Chapter 27: Prokaryotes Concept 27.1: Structural and functional adaptations contribute to prokaryotic success - Prokaryotes are unicellular o Some colonial forms - Range in size from 1-5 micrometer o Thiomargarita namibiensis (750 micrometers) - No membrane-bound organelles - Circular chromosomes Prokaryote cells have a variety of shapes - The three most common shapes are spheres (cocci), rods (bacilli), and spirals (spirilli) Cell Surface Structures - Cell Wall o Maintains cell shape, provides physical protection, prevents cell from bursting in a hypotonic environment o Composed of peptidoglycan in bacteria o May also have an outer phospholipid membrane - A capsule (a sticky layer of polysaccharide or protein) may cover the cell wall of many prokaryotes - Fimbriae and pilli allow prokaryotes to stick to their substrate or other individuals in a colony Motility - Motile bacteria move by means of flagella o Structurally different from eukaryotic flagella - In a heterogeneous environment bacteria exhibit taxis (ability to move forward or away from certain stimuli) o E.g. positive chemo-taxis moving toward a chemical stimulus Internal Organization - Prokaryotes do not have membrane-bound organelles - Some do have specialized membranes that perform metabolic functions Genomic Organization
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This note was uploaded on 02/14/2011 for the course BIOL 1201 taught by Professor Wishtichusen during the Spring '07 term at LSU.

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notes 2 - Chapter 27: Prokaryotes Concept 27.1: Structural...

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