Comparison of types of cell death: apoptosis and necrosis

Cell death is an essential factor in many biological processes including development. In addition, it contributes to disease states such as cancer. Two main types of cell death have been identified: apoptosis and necrosis. Necrosis occurs when cells are irreversibly damaged by an external trauma. In contrast, apoptosis is thought to be a physiological form of cell death whereby a cell provokes its own demise in response to a stimulus. The practical described here is an investigation into the two types of cell death: necrosis (induced by sodium azide) and apoptosis (induced by sodium chromate) that has been delivered to undergraduate students during several years. Key features that differ between these two types of cells death — loss of membrane integrity and internucleosomal DNA fragmentation — are illustrated in this paper. Model data is provided to allow this exercise to also be presented as a workshop.