Question

Suggest a reason why animals that live in cold climates tend to have higher proportions of polyunsaturated fatty acid residues in their lipids than do animals that live in warm climates.

Short answer

Animals in cold climates have more polyunsaturated fatty acids to keep cell membranes fluid.

Step-by-step solution

Understand the Relationship between Fatty Acids and Temperature

Fatty acids in lipids can be either saturated or polyunsaturated. Saturated fatty acids tend to be more solid at room temperature, whereas polyunsaturated fatty acids remain liquid at lower temperatures. This is because polyunsaturated fatty acids have multiple double bonds that prevent them from packing closely together.

Identify the Effect of Cold Climates on Cellular Membranes

In cold climates, temperatures are low, which can cause cell membranes to become too rigid. Animals in these environments need more flexible cell membranes to maintain proper cellular function.

Explain the Role of Polyunsaturated Fatty Acids

Polyunsaturated fatty acids help maintain membrane fluidity at lower temperatures. Their multiple double bonds prevent the fatty acids from packing tightly, thus ensuring that the lipid bilayer remains flexible and functional even in the cold.

Conclusion

Therefore, animals that live in cold climates have higher proportions of polyunsaturated fatty acid residues in their lipids to keep their cell membranes adequately fluid and functional despite the lower temperatures.

Key concepts

Lipid Membrane Fluidity

Lipid membrane fluidity is crucial for the proper functioning of cell membranes. The membrane must be flexible enough to allow proteins and lipids to move freely within it, facilitating various cellular processes like nutrient absorption, waste expulsion, and signal transduction. The type of fatty acids in the membrane significantly impacts its fluidity. Polyunsaturated fatty acids have multiple double bonds that introduce kinks in their structure, preventing them from packing tightly together. This loose packing enhances fluidity, especially necessary in colder climates where temperatures can make membranes too rigid. Therefore, polyunsaturated fatty acids help maintain a flexible and functional membrane, ensuring cellular activities occur smoothly even when the ambient temperature drops.

Fatty Acids

Fatty acids are essential components of lipids, which make up cell membranes. They can be classified into saturated and polyunsaturated fatty acids. Saturated fatty acids have no double bonds, making them straight and able to pack closely together, resulting in a more solid structure at room temperature. In contrast, polyunsaturated fatty acids have multiple double bonds, which introduce kinks, preventing tight packing. This difference has significant implications for membrane fluidity and function. Because polyunsaturated fatty acids don't pack tightly, they help maintain a more liquid membrane, essential for proper cellular function. This loose packing is especially beneficial for organisms in cold climates, where maintaining membrane fluidity is critical for survival.

Temperature Adaptation

Temperature adaptation is key for organisms living in varying climates. Animals in cold environments have adapted by incorporating higher proportions of polyunsaturated fatty acids in their membranes. These fatty acids remain fluid at lower temperatures, preventing the membrane from becoming too rigid. This adaptation is vital for several reasons:

• Cellular processes: Flexibility in membranes allows necessary processes like enzyme activity and nutrient transport.
• Survival: Maintaining membrane fluidity ensures that cells function correctly, which is crucial for the survival of the organism.
• Structural Integrity: A flexible membrane helps protect cells from physical stresses caused by freezing temperatures.

By increasing the amount of polyunsaturated fatty acids, animals in cold climates ensure their membranes remain functional, supporting effective cellular and overall biological activity.