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Chapter 23 “Bacteria”

Chapter 23 “Bacteria”. 23.1 Prokaryotes: Bacteria are…. Unicellular prokaryotes with no nucleus or membrane organelles Ubiquitous Most are helpful Classified by their biochemistry, habitats, and methods of energy use and obtaining food Heliobacter pylori RNA, Eukarya and Archaea.

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Chapter 23 “Bacteria”

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  1. Chapter 23 “Bacteria”

  2. 23.1 Prokaryotes: Bacteria are… • Unicellular prokaryotes with no nucleus or membrane organelles • Ubiquitous • Most are helpful • Classified by their biochemistry, habitats, and methods of energy use and obtaining food • Heliobacter pylori • RNA, Eukarya and Archaea

  3. Two Groups • Domain - Archaea • Kingdom – Archaebacteria • Lack peptidoglycan (protein carbohydrate) in cell wall • AKA Extremophiles - • Halophiles (love salt) • Methanogens (convert H2 and CO2 into methane gas) • Thermoacidophiles (love acidic, hot environments) • First organisms to colonize primitive earth

  4. Domain – BacteriaKingdom – Eubacteria • Eu = True • 3 basic shapes • Bacilli – rod shaped. E. coli, Bacillus anthracis • Cocci – spherical shaped. Staphylococcus aureus, Streptococcus pyogenes • Spirilla – spiral shaped. Spirochette, Syphilis

  5. Staining properties • Groups Eubacteria in two groups • Gram Staining • Gram Positive – Gram stain purple with crystal violet due to thick layer of peptidoglycan. Easier to kill with antibiotics • Gram Negative – Gram stain pink with safranin. Hard to kill with antibiotics due to thin layer of peptidoglycan Gram PositiveGram Negative

  6. Important Bacteria: The good, the bad, the ugly • Nitrogen fixing bacteria Rhizobium fix N2 into the root nodules of legumes • Eschericheri coli and Salmonella sp. cause food poisoning • Gram positive Clostridium botulinum causes botulism • Gram positive Lactobacilli make yogurt • Bacillus anthracis caused anthrax • Actinomycetes make antibiotics such as streptomycin and tetracyclin • Cyanobacteria are photosynthetic • Gram negative Spirochetes cause Lyme disease, syphyllis • Gram negative Chlamydia cause an STI

  7. More Bacterial Roles • Fermentation of milk products – sour cream, yogurt, buttermilk • Production of cheese • Fermentation to produce wine, sauerkraut, pickles • Mining and oil spill cleanup – Bioremediation • Biotechnology

  8. 23.2 Biology of Prokaryotes: Basic Structure • Cell Wall • Plasma membrane • Ribosomes • Circular DNA • Pili (hairs) for adherence to host cells • Flagella (protein) for movement, capsule (made of polysaccharides) for attachment.

  9. Endospores • Produced by Gram + (usually Bacillus and Clostridium) • A structure which encloses and protects the bacterial DNA • Dormant structure to survive adverse conditions (heat, cold, dryness, chemicals, radiation)

  10. Methods of Respiration • Obligate aerobic bacteria must have oxygen; (Tuberculosis bacteria) • Obligate anaerobes die if oxygen is present; (Tetanus bacteria that causes lockjaw) • Facultative anaerobes do not need oxygen, but don’t die if oxygen is present; (E. coli) • Remember: anaerobes carry on fermentation, while aerobes carry on cellular respiration

  11. Nutrition • Heterotrophic or autotrophic • Saprophytes – feed off dead, decaying material • Autotrophs – capable of making their own food; photoautotrophs photosynthesize, or chemoautotrophs oxidize inorganic compounds to release energy (ammonia, NH3) to form nitrite (NO2) • Heterotrophs – saprophytes (feed off decaying organic matter) or chemoheterotrophs, like us

  12. Reproduction Asexually by binary fission • Conjugation - Sexual reproductive method . Two bacteria form a conjugation bridge or tube between them • Pili hold the bacteria together • DNA is transferred from one bacteria to the other 

  13. Recombination • Transformation- bacteria pick up pieces of DNA from other dead bacterial cells • New bacterium is genetically different from original • Remember Griffith? Transduction – when a virus picks up a piece of DNA and transfers it to another bacterium

  14. 24.3 Bacteria and Humans • Pathogens – disease causing agents (Pathology – science of studying diseases) • Can produce poisonous toxins (poisons) • Endotoxins are made of lipids and carbohydrates by Gram negative bacteria and released after the bacteria die (cause high fever, circulatory vessel damage) E. coli • Exotoxins are made of protein by Gram + bacteria;secreted into environment. Clostridium tetani

  15. To fight them • Antibiotics interfere with cellular functions (Penicillin interferes with synthesis of the cell wall; tetracycline interferes with protein synthesis) • Some antibiotics are made by Actinomycetes bacteria or fungi (penicillin) • Broad-spectrum antibiotics affect a wide variety of organisms • Bacteria can mutate and become antibiotic resistant (often results from overuse of antibiotics) • MERSA

  16. Antibacterial Agents • Disinfectants – inhibits growth on a non-living surface – bleach, ammonia • Antiseptics– inhibits growth on a living surface – alcohol, hydrogen peroxide • Sterilization – high heat or chemicals that kills bacteria

  17. Diseases caused by bacteria • Anthrax • Botulism • Cholera • Cavities • Gonorrhea • Syphilis • Tetanus • Staph Infection (MRSA) • Food Poisoning • Lyme Disease • Diphtheria • Tuberculosis • Escherichia coli O157: H7 • Leprosy • Meningitis • Strep throat • Whooping cough (Pertussis) • Food poisoning *Results from decay of foods and production of toxins *33 million people/year get “stomach flu” *Seafood accounts for 20 – 25% of cases *33% of all raw poultry tests + for Staphylococcus *1 in every 200 eggs has Salmonella

  18. 4 C’s of Food Safety Chill your foods Cook your food to the proper temperature Clean food and cooking surfaces Combat Cross Contamination

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