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Prokaryotes

Prokaryotes. Prokaryotes. Microscopic, unicellular cells that may form colonies The three most common of which are spheres ( cocci ), rods (bacilli), and spirals. Cell Surface Structure. The cell wall of many prokaryotes is covered by a capsule, a sticky layer of polysaccharide or protein

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Prokaryotes

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  1. Prokaryotes

  2. Prokaryotes • Microscopic, unicellular cells that may form colonies • The three most common of which are spheres (cocci), rods (bacilli), and spirals

  3. Cell Surface Structure • The cell wall of many prokaryotes is covered by a capsule, a sticky layer of polysaccharide or protein • Adhere to molecules • fimbriae and pili • Protection

  4. Cell Surface Structure Gram + bacteria contain large amounts of peptidoglycan Gram – bacteria contain greater amounts of lipopolysaccharides

  5. Motility • propel themselves by flagella • exhibit taxis • ability to move toward or away from certain stimuli

  6. Genome • a ring of DNA that is not surrounded by a membrane and that is located in a nucleoid region • Some have smaller rings of DNA called plasmids

  7. Variation • Nutrition types • Photoautotrophy • Chemoautotrophy • Photoheterotrophy • Chemoheterotrophy • Metabolism • varies with respect to oxygen

  8. Archaea • Some archaea live in extreme environments • very hot environments • high saline environments

  9. Gene Transfer and Genetic Recombination • Transformation • alteration of a bacterial cell’s genotype and phenotype by the uptake of naked, foreign DNA from the surrounding environment

  10. Gene Transfer and Genetic Recombination • Transduction • phages carry bacterial genes from one host cell to another

  11. Gene Transfer and Genetic Recombination • Conjugation • direct transfer of genetic material between bacterial cells that are temporarily joined • The transfer is one-way: One cell (“male”) donates DNA, and its “mate” (“female”) receives the genes • ability to form a sex pilus and donate DNA, results from an F (for fertility) factor

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