Bacteria

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 Great Salt Lake, UT The Dead Sea, Israel

 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

 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

 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  coccus  Rods  bacillus  Spiral  spirillum

 Cell Arrangement  Diplo – cells are paired  Staphylo – cells are in grape-like clusters  Strepto – 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 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

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

 Convert N 2 gas into ammonia (NH 3 )  Convert ammonia (NH 3 ) to nitrite (NO 2 - ) and nitrate (NO 3 - )  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 Nitrogen fixation Bacteria on legume roots

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

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 TuberculosisScarlet feverRocky Mountain spotted fever Bacterial pneumonia SyphilisTetanus BotulismGonorrheaEar infections Strep throatChlamydiaBoils Staph infectionsDiphtheriaLyme disease