Term
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Definition
Must have O2 as the terminal electron acceptor
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Term
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Definition
Use Oxygen when available, but can utilize anaerobic pathways as well
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Term
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Definition
Occupy niches with limited oxygen level--2 to 10% O2 |
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Term
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Definition
Are killed by even small amounts of O2
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Term
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Definition
Live in moderately salty habitats such as seawater (0.4M NaCl). Many are obligate halophiles |
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Term
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Definition
Grow at higher salt concentrations, approaching saturation
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Term
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Definition
Cannot tolerate moderate salt concentrations
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Term
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Definition
Species can live in a range of conditions from no salt to moderate levels |
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Term
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Definition
Growth below 20 degress celsius
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Term
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Definition
Growth at 20 to 44 degrees celsius |
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Term
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Definition
Growth at 44 to 70 degrees celsius
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Term
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Definition
Growth above 70 degrees celsius |
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Term
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Definition
Microbes that grow at low pH (below pH 3)
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Term
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Definition
pH 5-8. Most human pathogens
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Term
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Definition
Grow at high pH (above pH 9) |
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Term
| How have aerobes adapted to tolerate the presence of toxic oxygen products? |
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Definition
By removing the damaging effects with protective enzymes |
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Term
| Why is water activity important for microbial growth? What changes water activity? |
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Definition
Water activity can be changedby the amount of solutes and surfaces around |
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Term
| What is an osmoprotectant and why is it needed? |
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Definition
They are compatible solutes used to increase a cell's internal osmotic concentration and prevent further shrinking or swelling of the cell |
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Term
| How do acidophiles and alkaliphiles manage to grow at the extremes of pH? |
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Definition
They use: - Proton/Ion exchange mechanisms
- K+/H+ antiporter to remove internal protons
- Na+/H+ antiporter to bring protons into the cell
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Term
| What are the ranges of temperature, pH, and osmotic pressure that are compatible wih the growth of bacteria and archaea? |
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Definition
Temperature: -10 to 110 degress celsius pH: 0 to 14 Osmotic pressure: Low to high concentrations
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Term
| How does actiity of superoxide dismutase differ from that of superoxide reductase? |
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Definition
Superoxide reductase involves cytochrome c being oxidized, while superoxide dismutase does not. Also, superoxide dismutase has O2 as a byproduct. |
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Term
| If anaerobes cannot live in oxygen, how do they incorporate oxygen into their cellular components? |
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Definition
They use oxygen in a different form, such as water or carbon dioxide. The only form that is toxic is oxygen gas. |
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Term
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Definition
The vapor pressure of air over a substance divided by the vapor pressure over pure water |
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Term
| When a cell is in an environment of low water activity, what happens to cellular water? |
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Definition
If solute concentration is higher in the medium than in the cell, water leaves the cell and the cell membrane collapses inward--plasmolysis
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Term
| Adaption methods to life at high temperatures |
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Definition
- Protein structure stabilized by a variety of means
- More H bonds
- more proline
- chaperones
- Histone-like proteins stabilize DNA
- Membrane stabilized by variety of means
- more saturated, more branched, and higher molecular weight lipids
- ether linkages (archaeal membranes)
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