TEST 2 Notes bio1202

TEST 2 Notes bio1202 - Chapter 27: Prokaryotes One thing...

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Chapter 27: Prokaryotes One thing that E. coli and other bacteria have in common with eukaryotes is the presence of ribosomes. Concept 27.1: Structural and functional adaptations contribute to prokaryotic success o Prokaryotes are unicellular Some colonial forms o Range in size from 1-5 micrometers Thiomargarita namibiensis (750 micrometers) o No membrane-bound organelles o Circular chromosomes o Prokaryotic cells have a variety of shapes The 3 most common are spheres (cocci), rods (bacilli), and spirals (spirilli) o 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 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 Gram-negative bacteria have less peptidoglycan than gram-positive cells and their cell walls are more complex structurally. o Motility Motile bacteria move by means of flagellae Structurally different from eukaryotic flagella In a heterozygous environment, bacteria exhibit taxis (ability to move toward or away from certain stimuli)
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E.g., positive chemotaxis-moving toward a chemical stimulus
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TEST 2 Notes bio1202 - Chapter 27: Prokaryotes One thing...

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