Ch. 27 Bacterial Characteristics and Diversity (Exam 4).docx

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Department
Biology
Course Code
BIOL 110
Professor
D R.J O H N P E L E S

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Biology 110 Dr. Peles Date: / / . Bacterial Characteristics and Diversity: Chapter 27 I. General Characteristics of Bacteria A. Structure 1. Unicellular prokaryotes i. Prokaryotic characteristics a. No internal compartmentalization (no organelles) b. Less DNA than eukaryotes (one circular chromosome, plasmids) c. DNA not complexed with proteins d. Much smaller in size than eukaryotes (rely on diffusion) 2. Cell Wall i. Peptidoglycan- Polymer of peptides and polysaccharides ii. Glycocalyx- Capsule of peptides and polysaccharide3s that enclose peptidoglycan 200nm Capsulele Fiurree 2277..44 3. Diversity of Shapes Bacterial Shapes 1μm 2 μm 5μmm (a)Sphercalcoccii)) b)Rood shaped baciillllii))pialla B. Reproduction and Growth 1. Asexual reproduction by binary fission ~ 1 ~ Biology 110 Dr. Peles Date: / / . 2. Rapid, S-shaped growth C. Adaptation 1. Acquisition of new genes i. Transformation- Genes are taken up from the surrounding environment ii. Transduction- Genes are transferred among bacteria by viruses iii. Conjugation- Direct transfer of genes from one bacteria to another iv. Antibiotic- chemical that inhibits the growth of a microorganism v. Plasmid Characteristics a. Self-replicating, small ring of DNA that carries accessory genes b. Genes are not necessary for bacterial survival but can confer selective advantages for the bacteria 2. Endospore formation i. Endospore- Thick coated cell that is resistant to harsh conditions D. Metabolism 1. Diversity of energy and carbon requirements i. Autotroph- Organism with the ability to utilize energy from sunlight or other sources to manufacture organic molecules from carbon ii. Heterotroph- Organism relies on organic molecules formed by autotrophs as an energy source Energy and Carbon Requirements Mode of Nutrition Energy Source Carbon Source Autotroph Photoautotroph Light CO₂ Chemoautotroph Inorganic chemicals CO₂ Heterotroph Photoheterotroph Light Organic Compounds ~ 2 ~ Biology 110 Dr. Peles Date: / / . Chemoheterotrop Organic compounds Organic Compounds h 2. Diversity of nitrogen requirements Nitrogen Metabolism Nitrogen Fixation N₂ → NH₄⁺ Nitrification NH₄⁺ → NO₂⁻ Nitrification NO₂⁻ → NO₃⁻ Ammonification Organic N → NH₄⁺ Denitrification NO₃⁻ → N₂ 3. Diversity of oxygen requirements Oxygen Requirements Condition O₂ Utilization Obligate aerobe O₂ required; No growth without O₂ Facultative anaerobe O₂ used if present; Fermentation possible Obligate anaerobe O₂ not required; O₂ toxic to cell II. Identifying groups of Eubacteria A. Techniques for Identifying Bacteria 1. Shape 2. Gram stain LLiippooppoollyyssaacccchhaarriiddee i. Gram positive- Large amounts of peptidoglycan that traps violet Ouutteerr Ceewaallll Peeppttiiddooggllyyccaann Ceewaallllmembbrraannee llaayyeerr dye Peeppttiiddooggllyyccaann llaayyeerr Pllmaamembbrraannee Pllmaamembbrraannee ii.
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