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Bacteria

Bacteria. 2 Kingdoms : Eubacteria (in domain Bacteria) & Archaebacteria (in domain Archae) - eubacteria larger of 2 kingdoms, cell walls contain peptidoglycan (a carbohydrate) - archaebacteria lack peptido. Thought to be ancestors of eukaryotes.

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Bacteria

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  1. Bacteria 2 Kingdoms : Eubacteria (in domain Bacteria) & Archaebacteria (in domain Archae) - eubacteria larger of 2 kingdoms, cell walls contain peptidoglycan (a carbohydrate) - archaebacteria lack peptido. Thought to be ancestors of eukaryotes. Identification is mostly by shape: Bacilli – are rod shaped Cocci are spherical Spirilla are spiral or corkscrew

  2. Cell walls: one identification technique is done by Gram Staining. (some retain dye where others do not) Has to do with lipid and peptidoglycan content in cell wall • Movement – can be by flagella. Others may glide or twist (spirilla). Others don’t move at all. • Gets energy – some are autotrophic, some are heterotrophic

  3. Growth & reproduction – bacteria produce 2 daughter cells in a process called binary fission. Some produce spores (endospore) where they remain dormant until favorable conditions arise. • Many bacteria are decomposers. • Others “fix” nitrogen. These bacteria attach to certain plant roots and convert atmospheric nitrogen to a useable form that the plant can use (process is called nitrogen fixation)

  4. Disease: some bacteria are pathogenic (disease causing). Done either by • Damaging tissues • Releasing toxins • Antibiotics – used to control bacterial growth. (increased life expectancy)

  5. Bacteria can be useful to humans: • Used in food industry (pickles, sauerkraut, vinegar, cheese, yogurt, buttermilk, sour crm) • Controlling growth: • Sterilization – by subjecting to high heat or chemical treatment • Refrigeration – reduces growth for awhile

  6. Viruses • Definition: particles of nucleic acid and protein that reproduce only by infecting living cells • Viruses are coated by protein (called a capsid)

  7. Viral Infections • Lytic – virus enters host cell, and makes copies. Cell enlarges, then is destroyed (bursts) • Lysogenic – viral particle moves into cell & replicates. Does not destroy host but is then replicated along with host cell.

  8. Retroviruses • Contain RNA. They turn RNA into DNA using cell materials. (Retro) • These viruses are responsible for some cancers in animals. Also HIV (the virus causing AIDS)

  9. Prions • No genetic material – just protein. (Mad Cow Disease). Particles show up in nerve tissue (brain) Viroids • A single strand of RNA that has no capsid. These affect mostly plants

  10. Host Cell Specificity • Viruses are restricted to certain kinds of cells. Example: viruses that affect plants do not affect animals

  11. No genetic material – just protein. (Mad Cow Disease). Particles show up in nerve tissue (brain)

  12. Important viral diseases in Humans • AIDS – transmitted by sexual contact, contaminated blood • Hepatitis A & B – same • Influenza (flu) – acquired by inhalation • Mumps – same • Rabies – Transmitted by animal bite • SARS - inhalation

  13. Important bacterial diseases in humans • Bubonic Plague – transmitted by flea bite • Cavities – Dense collections of oral bacteria • Tuberculosis – inhalation • Lyme disease – bite from infected tick • Cholera – aquired from drinking contaminated water

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