W1L2 - Prokaryotes - Bacteria & Archaea

W1L2 - Prokaryotes - Bacteria & Archaea - Biol 5B...

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1 Biol 5B: Organismal Biology Spring ’09 WEEK 1; Lecture 2 Prokaryotes: Bacteria and Archaea Prokaryotes • Prokaryotes thrive almost everywhere, including places too acidic, salty, cold, or hot for most other organisms Structural & Functional Adaptations Most prokaryotes are unicellular, although some species form colonies Most prokaryotic cells are 0.5 5 μ m, much smaller than the 10 100 μ m of many eukaryotic cells Prokaryotic cells have a variety of shapes The three most common shapes are spheres (cocci), rods (bacilli), and spirals (a) Spherical (cocci) 1 μm (b) Rod-shaped (bacilli) 2 μm (c) Spiral 5 μm
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2 Structural & Functional Adaptations Eukaryote cell walls are made of cellulose or chitin Bacterial cell walls contain peptidoglycan , a network of sugar polymers cross-linked by polypeptides Archaea contain polysaccharides and proteins but lack peptidoglycan Many antibiotics target peptidoglycan and damage bacterial cell walls Structural & Functional Adaptations Fimbriae Capsule Cell wall Circular chromosome Internal organization Flagella Sex pilus Motility Most motile bacteria propel themselves by flagella that are structurally and functionally different from eukaryotic flagella In a heterogeneous environment, many bacteria exhibit taxis , the ability to move toward or away from certain stimuli Show video Fig. 27-6 Flagellum Filament Hook Basal apparatus Cell wall Plasma membrane 50 nm
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3 Reproduction and Adaptation
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This note was uploaded on 03/18/2010 for the course OMJO;IJ ;skjdnf taught by Professor Sadofi during the Spring '10 term at SUNY Plattsburgh.

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W1L2 - Prokaryotes - Bacteria & Archaea - Biol 5B...

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