Bacteria. Classification of Bacteria Archaebacteria The extremists Oxygen – free environments...
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Transcript of Bacteria. Classification of Bacteria Archaebacteria The extremists Oxygen – free environments...
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 BacteriaMicroscopic, simple, livingProkaryotic, no true nucleusNon-membrane bound organellesMore complex than viruses but less
than living, cellular organisms Ribosomes smaller Inherited information held in single
circular chromosome
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 AdaptationDiversity of metabolism
Obligate aerobes Bacteria that require oxygen for cellular
respiration
Mycobacterium tuberculosis Person with tb
Types of BacteriaComplex
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 survivalEndospores
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
ConjugationSexual reproductionOne bacterium transfers all or part of its
chromosome to anotherPilus (pili)
Bridge-like structure Connects two cells Used to transfer genetic material
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
Nitrogen fixation
Bacteria on legume roots
Recycling of nutrientsCyanobacteria
Replenish supply of oxygen in atmosphereAutotrophic 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