Question

How do phospholipids contribute flexibility to cell membrane structure?

a. The phospholipids containing unsaturated fatty acids cannot be tightly packed which provides membrane flexibility.
b. The phospholipids containing saturated fatty acids cannot be tightly packed which provides membrane rigdidity.
c. The two fatty acid chains are flexible as they are unsaturated and provide the flexibility.
d. The two fatty acid chains are saturated. Embedded cholesterol and proteins provide the flexibility.

Answer 1

Unsaturated fatty acids in phospholipids contribute flexibility to cell membrane structure.

Step-by-step explanation:

The flexibility of cell membrane structure is contributed by the presence of unsaturated fatty acids in phospholipids. Unsaturated fatty acids contain double bonds between adjacent carbon atoms, causing a bend in the carbon string. This bend results in a more fluid membrane, as the kinks in the fatty acid tails elbow adjacent phospholipid molecules away, maintaining space between them.

The presence of saturated fatty acids, which have no double bonds and therefore have straight tails, would allow for tighter packing, resulting in a more rigid membrane. However, the kinks in the unsaturated fatty acid tails create space, providing "elbow room" that helps the membrane maintain its fluid nature, essential for cell function, especially in cold environments where membrane fluidity is crucial for survival.

This flexibility is important in cold environments, as it prevents the membrane from solidifying. By adapting the proportion of unsaturated fatty acids, organisms can regulate the fluidity of their cell membranes in response to temperature changes.