Chapter 27

Chapter 27 - Chapter 27 Prokaryotes I. II. III. IV. V....

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Chapter 27 – Prokaryotes I. Northern elephant seals were nearly hunted to extinction in the early 20 th century. Their populations have since recovered, but they have low genetic variability. This is an example of ___. a. Bottleneck effect II. One thing that E.Coli and other bacteria have in common with eukaryotes is the presence of what? a. Chloroplasts i. P - Do not have membrane bound organelle b. Mitochondria i. P - Do not have membrane bound organelle c. Nucleus i. DUH! d. Ribosomes i. Is in both III. Concept 27.1: Structural and functional adaptations contribute to prokaryotic success a. Unicellular, single celled organelles i. Some colonial forms 1. Colony of single cells, each individual cell is still independent between one another b. Very small, range in size from 1-5 microns (1/1,000 of a mm) i. Thiomargarita namibiensis (750 microns) 1. Exception, very large for one c. No membrane-bound organelles i. All basic functions are carried out in cytoplasm, no departmental functions d. Circular chromosomes i. In contrast to Eukaryotes with linear chromosomes
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IV.Prokaryotic cells have a variety of shapes a. The three most common are spheres (cocci), rods (bacilli), and spirals (spirilli) V. Cell-surface Structures a. All prokaryotes have a Cell Wall i. Maintains cell shape, provides physical protection, prevents cell from bursting in a hypotonic environment ii. Composed of peptidoglycan in bacteria iii. May also have an outer phospholipids membrane iv. Gram positive (ones that remain purple) 1. Plasma membrane and cell wall v. Gram negative (turns red/pink) 1. Plasma membrane surrounding the cytoplasm, thin cell wall, and then outside the cell wall is another lipid membrane a. Because it’s thin, alcohol rinses that out and creates a red tint b. Capsule i. A capsule (a sticky layer of polysaccharide or protein) may cover the cell wall of many prokaryotes ii. Fimbriae and pilli allow prokaryotes to stick to their substrate or other individuals in a colony 1. Fimbriae – help bacteria to adhere to surfaces and are the stringy things sticking out of them a. Gonorrhea 2. Pillus/Pilli a. Helps in bacteria conjugation iii. Smooth Strain 1. Did have a capsule layer which was difficult for the immune system to completely eliminate them c. Motility i. Motile bacteria move by means of flagellae
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1. Structurally different from eukaryotic flagella ii. In a heterogeneous environment bacteria exhibit taxis (ability to move toward or away from certain stimuli)
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This note was uploaded on 02/26/2009 for the course BIOL 1202 taught by Professor Gregg during the Spring '08 term at LSU.

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Chapter 27 - Chapter 27 Prokaryotes I. II. III. IV. V....

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