Membrane computing is a computational model inspired from the structure and functions of a living cell. This book investigates and shows the capabilities and the power of membrane systems, demonstrates a classifier membrane system based on fuzzy logic and genetic algorithms, and adds channel formation rules to the theory of membrane systems. The mitochondrial functions of the living cell including energy production, cell aging and channel formation within a membrane are employed. The performance of the fuzzy classifier membrane system is measured. The channel formation rules are executed and added the feature of probable cell death to the theory of membrane systems. Killing rules of phagocytes are investigated to be added to the theory of membrane systems.