Molecules and Signalling

Cell membranes are selectively permeable. This means that they allow the movement of some molecules freely across them, but do not allow the free passage of others. In broad terms, there are three ways in which molecules move across membranes. These are the processes of diffusion, osmosis and active transport. In theses article we will discuss these three processes and consider the clinical relevance of them.

Cellular receptors are proteins which are essential for cell signalling. When a specific signalling molecule (ligand) binds to its corresponding receptor, this acts like a key unlocking a door. The binding of a ligand triggers a change in the receptor, which leads to a host of downstream signalling actions and changes inside the cell. While there are many different types of receptors, they can be broadly classified into cell surface receptors and intracellular receptors. This article will discuss the structure and function of the main types of receptors, with examples of their clinical relevance.

Enzymes are required for most, if not all, processes required for life. Enzymes catalyse a reaction by reducing the activation energy needed for the reaction to occur. However, enzymes need to be tightly regulated to ensure that levels of the product do not rise to undesired levels. Our articles on enzyme regulation will help you understand this.