BIOL 1202 Chapter : Chapter 27 Prokaryotes
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 3 most common are spheres (cocci), rods (bacilli), and spirals (spirilli) Motility: motile bacteria move by means of flagellae, structurally different from eukaryotic flagellae. 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. Internal organization: prokaryotes do not have membrane-bound organelles, some do have specialized membranes that perform metabolic functions. Genomic organization: prokaryotic chromosome (circular dna found in the nucleoid region, plasmid (smaller circular dna rings, additional genes not always necessary for basic survival, e. g. antibiotic resistance. Reproduction: prokaryotes reproduce quickly by binary fission, can divide every 1-3 hours, form of asexual reproduction, produces genetically identical daughter cells.
