Final answer:
Fish living in different temperature waters vary their membrane's phospholipid composition to maintain membrane fluidity; warm water fish with more saturated and cold water fish with more unsaturated fatty acids.
Step-by-step explanation:
The phospholipid composition of fish cell membranes varies between species that live in warm tropical waters and those in cold arctic waters to maintain similar fluidity. Tropical fish tend to have more saturated fatty acids in their membranes, resulting in straighter tails that are well-suited for the fluidity required in warmer temperatures. In contrast, cold-water fish have a higher proportion of unsaturated fatty acids, which have kinks due to the presence of double bonds, providing the necessary 'elbow room' to maintain fluidity in cold temperatures.
These adjustments in phospholipid composition illustrate the body's ability to maintain the fluidity of cellular membranes through non-covalent interactions. In colder environments, the increased presence of unsaturated fats with their kinked tails prevents tight packing of the membrane, thus avoiding solidification and rupture. This adaptive mechanism ensures the proper functioning of cellular processes across different temperature regimes.