Chapter 5 – Membrane Structure and Function
Introduction
Figure 5.1. The term “fluid mosaic model” was used to describe structure and function of cell membranes in the 1970s by Singer and Nicholson. However, this term only makes sense if you know what a mosaic is! Here is an example tile mosaic, where multiple different components (different tile colours and shapes) are combined to create a unified image. In a similar way, membranes are composed of many different molecules, each of which contributes to the function of the membrane as a whole. (credit: Anne Bedel, CC BY-SA 4.0 via Wikimedia Commons)
Cellular membranes have many functions due to the mosaic nature of their structure (Figure 5.1). The most basic of these functions includes defining cellular borders and maintaining whole cell function. The plasma membrane does this by separating the inside of the cell from the external environment. Other cellular membranes include those that enclose organelles within eukaryotic cells. This chapter will explore the structure and function of cellular membranes, the mechanisms used to transport substances across them, and the function of membranes in cell signalling.
Chapter Outline
5.1 Membrane Components and Structure
5.2 Selective Permeability and Solute Gradients
5.3 Passive Transmembrane Transport
5.4 Active Transmembrane Transport