BIOL 1002 Chapter : Chapter 27 Handout
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 m. Thiomargarita namibiensis (750 m: 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) Maintains cell shape, provides physical protection, prevents cell from bursting in a hypotonic environment. May also have an outer phospholipid membrane. Figure 27. 5: 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. Figure 27. 6: 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 toward a chemical stimulus.
