Cell membrane

 The cell membrane is an extremely pliable structure  

composed primarily of back-to-back phospholipids (a “bilayer”). 

Cholesterol is also present, which contributes to the fluidity of the membrane, 

There are various proteins embedded within the membrane that have a variety of functions.

A single phospholipid molecule has a phosphate group on one end, called the “head,”which have negativity charge making head polar and hydrophilic or water loving.

Hydrophilic attract on water on both extracellular and intracellular enviroment.

Two side-by-side chains of fatty acids that make up the lipid tails.

 The lipid tails, on the other hand, are uncharged, or nonpolar, and are hydrophobic—or “water fearing.” 

A hydrophobic molecule (or region of a molecule) repels and is repelled by water.

 Some lipid tails consist of saturated fatty acids and some contain unsaturated fatty acids. 

This combination adds to the fluidity of the tails that are constantly in motion.

Phospholipids are thus amphipathic molecules.

 An amphipathic molecule is one that contains both a hydrophilic and a hydrophobic region. 

In fact, soap works to remove oil and grease stains because it has amphipathic properties. 

The hydrophilic portion can dissolve in water while the hydrophobic portion can trap grease in micelles that then can be washed away.