BIOL 1202 Chapter : Bio Ch 27
Document Summary
Concept 27. 1: structural and functional adaptations contribute to prokaryotic success: prokaryotes are unicellular (some colonial forms, range in size from 1-5 (thiomargarita namibiensis (750), no membrane bound organelles, circular chromosomes. Prokaryotic cells have a variety of shapes: the three most common are spheres (cocci), rods (bacilli), and spirals (spirilli) Cell surface structures: cell wall, maintains cell shape, provides physical protection, prevents cell from bursting in a hypotonic environment, composed of peptidoglycan in bacteria, may also have an outer phospholipid membrane. Cell surface structure: 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 flagellae, structurally different from eukaryotic flagella. In a heterogeneous environment bacteria exhibit taxis (ability to move toward or away from certain stimuli: e. g. : positive chemotaxis -> moving towards a chemical stimulus.
