BIOL 1202 Chapter : Chapter 27
Document Summary
One thing that e. coli and other bacteria have in common with eukaryotes is the presences of ribosomes. Concept 27. 1: structural and functional adaptations contribute to prokaryotic success, prokaryotes are unicellular, some colonial forms, range in size from 1-5 micrometers, thiomargarita namibiensis ( 750 micrometers, 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, figure 27. 2. Cell-surface structures: cell wall, maintains cell shape, provides physical protection, prevents cell from bursting i a hypotonic environment, composed of peptidoglycan in bacteria, may also have an outer phospholipid membrane, figure 27. 3. Gram-negative bacteria have less peptidoglycan than gram-positive cells and their cell walls are more complex structurally. Motility: motile bacteria move by means of flagella, structurally different from eukaryotic flagella. In a heterogeneous environment bacteria exhibit taxis (ability to move toward or away from certain stimuli: example: positive chemotaxis-moving toward a chemical stimulus, figure 27. 6.
