Question

29. Which of the following statements regarding the fatty acid tails of phospholipids is FALSE?

(a) Phospholipids with unsaturated tails make the bilayer more fluid because the tails contain fewer hydrogen atoms and thus form fewer hydrogen bonds with each other.
(b) Saturated phospholipid tails pack more tightly against each other than do unsaturated tails.
(c) Most membrane phospholipids have one fully saturated tail.
(d) Phospholipid tails in a membrane can interact with each other via van der Waals interactions.
(e) Fatty acid tails vary in length.

Answer 1

(c) Most membrane phospholipids have one fully saturated tail.

Step-by-step explanation:

Answer 2

Most membrane phospholipids have two fully saturated tails, tightly packing together and increasing rigidity, making option (c) false. Unsaturated tails with double bonds introduce kinks, increasing fluidity, making option (a) true. Fatty acid tails can vary in length, further contributing to fluidity, making option (e) true.

Step-by-step explanation:

The fluidity of a phospholipid bilayer is influenced by the characteristics of the fatty acid tails. In contrast to the statement in option (c), most membrane phospholipids have two fully saturated tails. This saturation, along with the presence of van der Waals interactions, causes the tails to tightly pack together, making the bilayer more rigid. The presence of unsaturated tails (option a) with double bonds introduces kinks in the tails, preventing tight packing and increasing fluidity in the bilayer. Additionally, fatty acid tails can vary in length (option e), which also contributes to the fluidity of the membrane.