Phospholipids (WJEC A-level Biology)

This engaging lesson describes the relationship between the structure, properties and functions of phospholipids, focusing on its role in membranes. The PowerPoint has been designed to cover the second part of point (f) as detailed in AS unit 1, topic 1 of the WJEC A-level Biology specification and includes constant references to the previous lesson on triglycerides.

The role of a phospholipid in a cell membrane provides the backbone to the whole lesson. A quick quiz round called FAMILY AFFAIR, challenges the students to use their knowledge of the structure of a triglyceride to identify the shared features in a phospholipid. This then allows the differences to be introduced, such as the presence of a phosphate group in place of the third fatty acid. Moving forwards, the students will learn that the two fatty acid tails are hydrophobic whilst the phosphate head is hydrophilic which leads into a key discussion point where the class has to consider how it is possible for the phospholipids to be arranged when both the inside and outside of a cell is an aqueous solution. The outcome of the discussion is the introduction of the bilayer which is critical for the lesson in AS unit 1, topic 3 on the fluid mosaic model. The final part of the lesson explains how both facilitated diffusion and active transport mean that proteins are found floating in the cell membrane and this also helps to briefly prepare the students for upcoming topic 3 lessons.