chapt04_lecture - Microbiology: A Systems Approach, 2nd ed....

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Microbiology: A Systems Approach, 2 nd ed. Chapter 4: Prokaryotic Profiles- the Bacteria and Archae
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What are prokaryotes? What are eukaryotes? Which is the third domain?
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How are Prokaryotes Different from Eukaryotes? The way their DNA is packaged No nucleus Do not have complex organelles DNA as genetic material Ribosomes for protein synthesis Inclusion bodies The makeup of their cell wall Bacteria- peptidoglycan Archae- tough and made of other chemicals, distinct to them
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Structures common to all bacterial cells Cell membrane Cytoplasm Ribosomes One (or a few) chromosomes
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Structures found in most bacterial cells Cell wall Surface coating or glycocalyx
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Structures found in some bacterial cells Flagella Pili Fimbriae Capsules Slime layers Inclusions Actin cytoskeleton Endospores
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4.1 Prokaryotic Form and Function
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Figure 4.1
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4.2 External Structures Appendages : Cell extensions Common but not present on all species Can provide motility  ( flagella and axial filaments) Can be used for attachment and mating ( pili and fimbriae ) Surface Coating/Glycocalyx Capsule Slime layer
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Flagella Three parts: Filament, hook (sheath), and basal body Vary in both number and arrangement Polar arrangement: flagella attached at one or both ends of the cell Monotrichous - single flagellum Lophotrichous - small bunches or tufts of flagella emerging from the same site Amphitrichous - flagella on both ends Peritrichous - dispersed randomly over the structure of the cell
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Figure 4.2
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Figure 4.3
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Flagellar Function Primary function is to provided motility Chemotaxis - positive and negative Phototaxis Move by runs(counter clockwise) and tumbles
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Figure 4.4
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Axial Filaments/periplasmic flagella In spirochetes or corkscrew shaped bacteria A type of internal flagellum that is enclosed in the space between the cell wall and the cell membrane Involved in locomotion
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Figure 4.6
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Pili Elongate, rigid tubular structures Made of the protein pilin Found only in gram-negative bacteria Used in conjugation-  transfer of genetic materials between bacteria through physical contact
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Figure 4.8
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Fimbriae and Pilus Small, bristle-like fibers Most contain protein Tend to stick to each other and to surfaces Provides adhesion NO locomotion
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Figure 4.7
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The Glycocalyx Develops as a coating of repeating polysaccharide units, protein, or both Protects the cell Sometimes helps the cell adhere to the environment Differ among bacteria in thickness, organization, and chemical composition Slime layer- a loose shield that protects some bacteria from loss of water and nutrients Capsule - when the glycocalyx is bound more tightly to the cell and is denser and thicker
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Figure 4.9
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Functions of the Glycocalyx Formed by many pathogenic bacteria- protect the bacteria against phagocytes Important in formation of biofilms
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4.3
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chapt04_lecture - Microbiology: A Systems Approach, 2nd ed....

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