GRAM STAIN (12-4)
1. What is a gram stain?
- Staining technique to classify bacteria
- First stained with violet, treated by Gram’s solution, decolorized with alcohol, treated with safranine and the washed in water
- If the bacteria keeps the violet color (after being washed, etc) then it is Gram- positive and if it doesn’t keep the violet color, then it is Gram- negative
2. Deinococcus radiodurans has a positive Gram stain
HABITAT (12-4)
· Found in the cooling cells of nuclear reactors
· Found in a wide range of places
o Marslike granite beds of antartica
o Hot springs
o Llama fences
· Tolerates deserts and arctic tundra where dehydration damages most cells severly
· Placed in nuclear waste sites to clean it up
· “lives everywhere and nowhere
o Found in elephant dung too
o No one know’s its natural habitat is
REPRODUCTION (12-5)
· Transfer genes (horizontal transfer?)
· Sexual reproduction
· Cell divides only the cytoplasmic membrane and peptidogycan layer are used
o Other layers form on the surface as the new cell grows
· Early stage- found in pairs (two connected cells)
· Later- undergo mitosis, remain in clusters of four cells
o Within clusters keep 4-8 copies of its genome to help repair
BENEFICIAL FACTORS (12-6)
· Think it could survive radiation filled space and the harsh conditions on mars
o If genetically altered, could make medicines humans need on mars to help make the martian environment more earthlike
· ON EARTH!
o Currently designing variants that thrive in toxic waste sites
o Making mercury and toluene less dangerous substances
· Can stabilize contaminated metals and organic compounds inorder to prevent them from getting further into the water suppy and soil that is already contaminated by nuclear waste
INTERESTING FACTS: 12-9
· Impressive resistance to UV and ionizing radiation
· Can survive large doses of radiation and long periods without water
· Can stand a dose of radiation 1000 times more intense than that would prove lethal to a person
· People die after 50-100 rads of radiation, DR can survive to 1.5 to 3 million rads
· Think it could survive radiation filled space and the harsh conditions on mars
o If genetically altered, could make medicines humans need on mars to help make the martian environment more earthlike
· Nicknamed “Conan the Bacterium” because it was assumed to posses super DNA repair systems
· 1900 proteins in it
· Guiness book of world records- “world’s toughest bacterium”
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