Extremophiles
- Created by: JS007
- Created on: 09-01-18 12:32
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- Extremophiles
- Heat
- hyper-thermophiles survive at 70-110 DegC
- Problems: Proteins denature, DNA unwinds, ATP breaks down, cell membranes become more fluid
- Contain heat shock protein which refold denatured enzymes
- reverse DNA gyrase helps rewind DNA
- Hydrophobic amino acids are held at the core of proteins to increase stability
- The cytoplasm contains salts to stop molecules denaturing
- Cell membranes contain more saturated fatty acids to increase stability
- Many archaea have tetraethers in their cell wall, increasing stability
- mesophiles survive at 10-45 DegC (most microbes)
- psychrophiles survive at 10-20 DegC
- hyper-thermophiles survive at 70-110 DegC
- pH
- Acidophiles prefer low pH 1-5
- Problems: Proteins denature and metabolic processes stop
- Cell membranes are less permeable to protons
- Ion channels are smaller
- Cell may take on more K+ or Na+ ions to reduce the gradient in protons
- May actively pump protons out of the cell
- Cytoplasmic buffers
- neutrophiles prefer neutral pH 5-7
- alkaliphiles prefer high pH 8-12
- Acidophiles prefer low pH 1-5
- Salinity
- halophiles prefer high salt concentration
- Problem: salt disrupts osmosis and may cause the cell to burst or shrink
- May take on more K+ instead of Na+ which has less of an affect on osmosis
- Cytoplasmic buffers
- non-halophiles find a high salt concentration toxic
- halotolerant organisms are unaffected by salinity
- halophiles prefer high salt concentration
- Heat
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