Bacteria

1. Bacteria

2. Classification of Bacteria • Archaebacteria • The extremists • Oxygen – free environments • Produce methane • Concentrated salt water environments • Great Salt Lake, UT • The Dead Sea, Middle East • Hot, acidic waters of sulfur springs The Dead Sea, Israel The Great Salt Lake, UT

3. Eubacteria • The heterotrophs • Found everywhere • Need organic molecules as an energy source • Parasites • Absorb nutrients from living organisms • Saprobes • Organisms that feed on dead organisms or organic waste • Help recycle the nutrients contained in decomposing organisms Saprobe

4. The photosynthetic autotrophs • Obtain energy from light • Cyanobacteria (cyano, blue-green) • Trap the sun’s energy by photosynthesis using their blue-green pigment • Some are red or yellow • Found in ponds, streams and moist land • Composed of chains of cells

5. The Chemosynthetic autotrophs • Obtain energy from chemosynthetic breakdown of inorganic substances • sulfur or nitrogen compounds • Important in converting nitrogen in the atmosphere to forms readily used by plants Underwater sea vent

6. Structure of Bacteria • Microscopic, simple, living • Prokaryotic, no true nucleus • Non-membrane bound organelles • More complex than viruses but less than living, cellular organisms • Ribosomes smaller • Inherited information held in single circular chromosome

8. Classification of Bacteria • Shape • Spheres • coccus • Rods • bacillus • Spiral • spirillum

9. Cell Arrangement • Diplo– cells are paired • Staphylo– cells are in grape-like clusters • Strepto– cells are in long chains

10. Protection from osmotic pressure • Cell walls • Made of long chains of sugar linked by short chain amino acids • Prevent osmotic rupture • Most bacteria live in hypotonic environment • Water always enter in • Cell wall prevents bursting of cell • If ruptured, cell dies

11. Penicillin – Bacterial Killer? • Interferes with the enzyme that links the sugar chains in the cell wall • Bacteria growing in penicillin develop holes in their cell walls • Water enters, bacteria dies • Not effective in viruses and animals • Neither has cell walls • Nontoxic to plants • Plant cell wall is different structure from bacterial cell wall

12. Miracle Cure – The Story of Penicillin • Discovered by Alexander Fleming in 1928 • Produced from an airborne mold, Penicillium notatum • World’s first antibiotic • Purified in 1940 • Kills bacteria and inhibit their growth Penicillium notatum

13. Ecology and Adaptation • Diversity of metabolism • Obligate aerobes • Bacteria that require oxygen for cellular respiration Person with tb Mycobacterium tuberculosis

14. Obligate anaerobes • Cannot use oxygen • Are killed by it Syphilis - causing bacteria

15. Complex biochemical pathways • Green sulfur bacteria • Use hydrogen sulfide instead of water for photosynthesis • Produce sulfur instead of oxygen • Grow in anaerobic environments like lake sediments Green sulfur bacteria

16. Adaptations for survival • Endospores • Have hard outer covering • Resist drying out, boiling, freezing, many chemicals • Bacteria is in slow metabolism, does not reproduce • When in favorable conditions, germinates and gives rise to bacterial cell

17. Clostridium botulinum • Obligate anaerobes • Form endospores • Produces an extremely powerful toxin (poison) • Don’t die when exposed to oxygen • Can find their way into canned food • If not properly sterilized • endospores germinate • bacteria grow • produce their deadly toxin • Causes botulism

18. Clostridium tetani • Produces powerful nerve toxin • Causes often-fatal disease, tetanus • Endospores are found in every surface • Can enter wound easily, germinate and release toxin • Immunization is prevention

19. Reproduction

20. Binary Fission • Asexual reproduction • Copies its single chromosome • Copies attach to cell’s plasma membrane • Cells grow in size, two copies of the chromosome separate • Cell divides into two as partition forms between two new cells • Each cell has one copy of chromosome • Just like mitosis, but the whole organism is copied

21. Binary fission

22. Conjugation • Sexual reproduction • One bacterium transfers all or part of its chromosome to another • Pilus (pili) • Bridge-like structure • Connects two cells • Used to transfer genetic material

23. Conjugation

24. Economic Importance

25. Nitrogen fixation • Convert N2 gas into ammonia (NH3) • Convert ammonia (NH3) to nitrite (NO2-) and nitrate (NO3-) • Some form symbiotic relationship with peas, peanuts, and soybeans • Helps them grow better when nitrogen is lacking • When they are harvested, remaining roots add nitrogen to soil Bacteria on legume roots

26. Recycling of nutrients • Cyanobacteria • Replenish supply of oxygen in atmosphere • Autotrophic bacteria • Convert carbon dioxide in the air to the organic compounds that are passed to consumers in food chains and webs • All life depend on bacteria

27. Food and medicines • Used to produce vinegar, yogurt, butter, cheese, pickles, sauerkraut • Used to produce antibiotics to kill other bacteria • Streptomycin • Erythromycin • Chloromycetin • Kanamycin

28. Bacteria cause disease • Half of human disease is caused by bacteria