Question

Do the fatty acid tails of the phospholipids of a plasma membrane project into the water inside and outside the cell?

Answer 1

The fatty acid tails of the phospholipids in a cell's plasma membrane do not project into the water inside or outside the cell. They are arranged within the interior of the bilayer to avoid water due to their hydrophobic nature, while the hydrophilic heads interact with the aqueous environment.

Step-by-step explanation:

Cells are enclosed by a plasma membrane, which exhibits a characteristic structural feature known as the phospholipid bilayer. This bilayer is composed of phospholipids that are arranged tail-to-tail, with each phospholipid molecule consisting of a hydrophilic (water-loving) head and a hydrophobic (water-fearing) fatty acid tail.

The fatty acid tails are oriented towards the interior of the bilayer, shielded from the aqueous environment both inside and outside the cell. Conversely, the hydrophilic heads point outward, interacting with the intracellular and extracellular water.

This arrangement is critical for the membrane's function, contributing to its fluidity and dynamic nature. It is worth noting that the proportion of unsaturated fatty acids in the tails influences this fluidity, with a higher ratio of unsaturated to saturated fatty acids leading to increased fluidity. Thus, the fatty acid tails do not project into the water; rather, they face inward within the bilayer, avoiding exposure to the water, which is incompatible with their hydrophobic nature.

Answer 2

A plasma membrane is formed of two layers of phospholipids. That is why the membranes are also called phospholipid bilayer. the outer layer points inwards towards the cell and inner layer. the inner layer points towards the outer layer. I've drawn a pic and labelled it.