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Transcript
Bacteria Classification of Bacteria Archaebacteria The extremists Oxygen – free environments Concentrated salt water environments Produce methane Great Salt Lake, UT The Dead Sea, Middle East Hot, acidic waters of sulfur springs The Great Salt Lake, UT The Dead Sea, Israel Eubacteria The heterotrophs Saprobe 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 The photosynthetic autotrophs Obtain energy from light Cyanobacteria (cyano, blue-green) Trap the sun’s energy by photosynthesis using their bluegreen pigment Some are red or yellow Found in ponds, streams and moist land Composed of chains of cells 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 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 Classification of Bacteria Shape Spheres Rods coccus bacillus Spiral spirillum Cell Arrangement Diplo – cells are paired Staphylo Strepto – cells are in grape-like clusters – cells are in long chains 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 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 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 Ecology and Adaptation Diversity of metabolism Obligate aerobes Bacteria that require oxygen for cellular respiration Mycobacterium tuberculosis Person with tb Types of Bacteria Obligate anaerobes Cannot use oxygen Are killed by it Syphilis - causing bacteria Types of Bacteria 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 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 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 Clostridium Produces tetani 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 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 Binary fission 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 Conjugation 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 Bacteria on legume roots soil Recycling of nutrients Cyanobacteria Replenish Autotrophic supply of oxygen in atmosphere 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 Food and medicines Used to produce vinegar, yogurt, butter, cheese, pickles, sauerkraut Used to produce antibiotics to kill other bacteria Streptomycin Erythromycin Chloromycetin Kanamycin Bacteria cause disease Half of human disease is caused by bacteria Tuberculosis Scarlet fever Rocky Mountain spotted fever Bacterial pneumonia Botulism Syphilis Tetanus Gonorrhea Ear infections Strep throat Chlamydia Boils Staph infections Diphtheria Lyme disease
