Final answer:
Cold-blooded animals modulate the fatty acid composition of their membranes as a function of temperature to ensure consistent membrane fluidity. They increase unsaturated fatty acids in cold environments and increase saturated fatty acids in warm environments. Cholesterol acts as a buffer to maintain fluidity within a range of temperatures.
Step-by-step explanation:
It is important for cold-blooded animals (gecko, lizard, and fish) to modulate the fatty acid composition of their membranes as a function of temperature to ensure consistent membrane fluidity. In cold environments, decreasing temperatures can compress saturated fatty acids in the cell membranes, making them less fluid and more susceptible to rupturing. By increasing the number of unsaturated fatty acids, these animals are able to maintain the fluidity of their membranes. On the other hand, in warmer environments, increasing temperatures can increase the fluidity of membranes. By increasing the saturated fatty acid content, cold-blooded animals can adapt to these changing temperatures and maintain proper membrane function.
Animals also have an additional membrane constituent, cholesterol, that assists in maintaining fluidity. Cholesterol acts as a buffer, preventing lower temperatures from inhibiting fluidity and preventing increased temperatures from increasing fluidity too much. This allows the membrane to remain functional within a range of temperatures. Cholesterol also serves other functions in the membrane, such as organizing clusters of transmembrane proteins into lipid rafts.