Old farmhouses typically don\'t have the best insulation, because, you know, the

Question

Old farmhouses typically don't have the best insulation, because, you know, they were built before insulation was really invented. This makes some parts of the house a bit chilly in winter. During long cold spells, the porches barely stay above 5°C. This is 40°F which you know is like the frozen tundra to me! Quite a contrast with the situation in summer, when non-airconditioned porches get close to 35°C. This is close to 90°F which sounds quite lovely to me! However, to a cold-blooded animal, like a spider (named Lenny) that might live there all year round, this could make for a difficult living situation. Good thing for Lenny, animals are able to adapt each season that allow them to survive different conditions. Suppose the lipid composition of Lenny's cell membranes during the summer heat wave is: Percent saturated lipids: Average lipid chain length: 80% What changes would you expect to see during the winter months to allow Lenny to acclimated to the cold? b. Lenny has some hot soup on cold days during the winter months to keep him warm. This soup is loaded with salt. Yet somehow Lenny's cells don't take up this salt. How are his cells protected from the high salt concentration? You want to study the membranes in more detail, specifically two proteins you have identified, cantstopchemistrypuns and wontstopchemistrypuns. So you take some cells from Lenny (don't worry you didn't kill him), and expose them to a severe drop in ionic strength. You are able to separate cantstopchemistrypuns from the membrane but not wontstopchemistrypuns. What do you hypothesize about the locations of the two proteins in the membrane? Justify your hypothesis c.

Explanation / Answer

a) When temperature decreases, the composition of membrane lipids (phospholipid fatty acids) is expected to become more unsaturated to be able to maintain homeoviscosity. The phospholipid content of the plasma membrane fraction increased to 42 mole% of the total lipid following cold acclimation.The contents of the lipids may rise due to the cold acclimation . The length of the carbon molecule do change but it changes for unsaturated lipids molecule and not for saturated molecules. Membrane lipids became more unsaturated during cold acclimation, and a reversed response occurred during warm acclimation. So therefore , the percentage of saturated lipids decrease and unsaturated lipids increases.The lipids average length may increase after cold acclimation.

b)The cell membrane of the spider will be protected from the higher salty contents in the soup beacuse of the stablising agents present in the cell of the spider. These cells are activated upon the cold acclimation in the surrounding .Simply the lipids will combine to form higher lipids which helps and protect them from colder environment . But if the temperature is too less then the lipids and proteins became inactive and the whole metabolism will stop working and the spider will die.

c) If we want the to separate the 2 proteins from the cell we can do that but putting it to severe ionic strengths. But in this case 1 protein is separated but the other is not the reason is its location, we can easily commnet that cantstopchemistrypuns are Peripheral membrane proteins and located on the edges (they can be separated by chemicals)but the ones which don't get separated are called the Integral membrane proteins which are embedded directly within the lipid bilayer and these are very difficult to separate or didn't get separate.

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