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Unformatted text preview: 1) Extremophiles are microorganisms, usually from the Archeal domain, that grow under a wide variety of extreme conditions (temperature, pressure, pH, salt, etc.). Some of these extremophiles can even grow in temperatures up to 121°C, the sterilization temperature of an autoclave. Identifying the adaptations that allow these microorganisms to thrive at such high temperatures is an area of active research both for improving industrial processes (i.e biofuels) and exobiology. Recent studies of the membrane composition of found that the major lipids in these organisms are tetraether phospholipids and diether phospholipids. In the diagram the R represents a variety of head groups. A) Diagram what a membrane made up of diether phospholipids would look like. Compare this to eukaryotic cell membranes. B) Diagram what a membrane made up of tetraether phospholipids would look like. Compare this to eukaryotic cell membranes. C) Diagram what a membrane made up of a mixture of diether and tetraether phospholipids would look like. Compare this to eukaryotic cell membranes. D) Would you expect the ratio of tetraether to diether phospholipids in the thermophile's membrane to increase or decrease with increasing temperature? Give two reasons to justify your answer. E) Would you expect either of these phospholipids in the thermophiles's membrane to become more or less saturated as temperature increases? Explain your answer. F) It turns out that thermophiles don't modify the saturation state of the lipid in response to temperature. They do however introduce pentacyclic groups into the lipid structure in response to temperature (structure below). Studies have shown that increasing the number of these groups in the tetraether phospholipids allows them to pack more tightly together. Given this information would you expect more or fewer pentacyclic modifications as temperature increases? Explain your reasoning. Explain your reasoning....
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- Winter '09
- cell biology, Parietal cell