Lipids

Question 1

Describe the structural difference between a saturated and an unsaturated fatty acid. How does this difference impact their melting points?

Answer 1

Saturated fatty acids have only single bonds between carbon atoms, while unsaturated fatty acids have at least one double bond. The double bonds in unsaturated fatty acids introduce kinks, preventing tight packing and resulting in lower melting points compared to saturated fatty acids.

Question 2

Name three major classes of membrane lipids. Briefly describe their key structural features.

Answer 2

1) Glycerophospholipids: Consist of a glycerol backbone, two fatty acids, and a phosphate group linked to a polar head group.
2) Sphingolipids: Built on a sphingosine backbone with a fatty acid and a polar head group.
3) Sterols: Characterized by a rigid four-ring structure, with cholesterol being the most common example in animal cells.

Question 3

Explain the fluid mosaic model of membrane structure.

Answer 3

The fluid mosaic model describes the cell membrane as a dynamic structure composed of a fluid lipid bilayer with embedded proteins that can move laterally within the bilayer.