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Bacteria

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  1. Bacteria Our invisible friends

  2. Germ Theory of Disease • Joseph Lister – Aseptic Techniques • Robert Koch – Germ Theory • A specific microorganism causes a specific disease

  3. Bacteria are prokaryotes • Pro – before • Karyon – nucleus • The simplest forms of life are prokaryotes. • Earth’s first cells were prokaryotes.

  4. Lots of Them! • Prokaryotes are Earth’s most abundant life forms. • They can survive in many environments. • They can get energy from many different sources.

  5. Prokaryote Review • Mostly single-celled • No nucleus or organelles • Circular chromosomes • Cell walls • Reproduce mostly asexually • Anaerobic or aerobic • Heterotrophic or autotrophic

  6. Archaebacteria • Methane producers – anaerobic • Halophiles • Halo = salt • Philia = love • Thermophiles • Thermo = heat

  7. Eubacteria • Parasitic heterotrophs (Streptococcus) • Saprophages • Sapro = death • Phage = eat • Cyanobacteria (blue-green algae) • Photosynthetic • Chemosynthetic autotrophs (Rhizobium)

  8. Bacteria Structure Chromosomes – found in cytoplasm Pili – hairlike structures made of protein; help bacteria attach to surfaces Capsule – layer outside cell wall; protects cell from white blood cells and antibiotics; keeps the cell from drying out

  9. Bacteria Structure

  10. Bacteria are Named by Shape • Cocci (ball-shaped) • Streptococcus mutans • Bacillus (rod-shaped) • Clostridium botulinum • Spirilli (spiral-shaped) • Treponema palladium

  11. Bacteria Reproduction Binary fission – asexual; division of bacteria into two identical cells Conjugation – sexual; two prokaryotes attach to each other and exchange genetic material; creates diversity among bacteria

  12. Bacteria Reproduction

  13. Bacteria Reproduction

  14. Why do we need bacteria? Our bodies use bacteria – not harmful; help prevent harmful bacteria from causing disease Foods – cheese, pickles yogurt all made with bacteria Medicines – make antibiotics such as penicillin

  15. Disease Causing Bacteria Only a small percentage of bacteria is harmful Cause disease in two ways: 1. multiply quickly so the body cannot defend itself ex. STDs, strep throat, acne 2. secrete a toxin that can be harmful ex. Cavities – use sugar for energy and secrete acid which can harm teeth

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