Chapter 3, Problem 1AC

Based on their structure, sketch and explain how phospholipids would organize themselves in water.

Summary Introduction

To explain:

Based on the structure, sketch and explain the way phospholipids would organize themselves in water.

Concept Introduction:

Lipid bilayer model consists of the organization of the lipids in the form of bilayers with a thickness of approximately $\text{5nm-10nm}$. It consists of the backbone of glycerol with two attached fatty acids. The third position of the carbon atom is composed of a phosphate functional group attached to a different functional group with a nitrogen atom. This confers a positive charge on the nitrogen atom thus making it hydrophilic for the surrounding water molecules. The glycerol backbone is hydrophobic for the charged polar water molecules.

Answer to Problem 1AC

Correct answer:

Explanation of Solution

Phospholipids are present in the membrane along with the other membrane proteins like the integral proteins and the extrinsic proteins. They form a bilayer in the membrane which is selectively permeable to a variety of solutes and solvents in the membrane. The phosphate group is polar and the fatty acid group is non-polar. The polar head group faces the outside of the membrane and the non-polar group faces the inside of the membrane.

Conclusion

The phospholipids form a bilayer in the membrane with the polar head group containing phosphate and a non-polar group containing the fatty acids in the cell membrane.