CH_21_pt.2_Outline

CH_21_pt.2_Outline - 21 (PART 2) Key Terms pathogen...

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21 (P ART  2)     PROKARYOTES Key Terms pathogen prokaryotic bacterial chromosome prokaryotic fission plasmid conjugation strain cyanobacteria proteobacteria chlamydias spirochaetes  endospores Archaeans methanogens extreme halophiles extreme thermophile pathogen antibiotic resistance Lecture Outline 21.1 Characteristics of Prokaryotic Cells A. Sizes and Shapes   1. Bacteria are prokaryotes—no nucleus or other membrane-bound organelles. 2. Typically, the length or width of bacteria falls between 1 and 10 micrometers. 3. Three basic shapes are common: a. coccus—spherical, b. bacillus (rod)—cylindrical, c. spirillum—helical. B. Structural Features 1. Nearly all bacteria have a cell wall, usually containing a tough mesh of  peptidoglycan , peptides  cross-linked with polysaccharides. a. Cell walls of Gram-positive bacteria retain a deep purple stain. b. Gram-negative bacteria lose the purple color when washed with alcohol and stain pink with a  counterstain. 2. Exterior to the cell wall is the  glycocalyx,  a jellylike capsule that helps bacterial cells attach to a  substrate or deter the host’s infection-fighting cells. 3. Two kinds of filamentous structures may be attached to the cell wall: a. The  bacterial flagellum  rotates like a propeller to pull the cell along. b. Pili  help bacteria attach to one another in conjugation, or help them attach to surfaces. C.  Metabolic Diversity 1. Photoautotrophic  bacteria synthesize their own organic compounds using sunlight as the energy  source and carbon dioxide as the carbon source. Bacteria, Viruses, and Protistans
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This note was uploaded on 06/11/2008 for the course BIO 2343 taught by Professor Rast during the Fall '08 term at Texas State.

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CH_21_pt.2_Outline - 21 (PART 2) Key Terms pathogen...

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