ABSTRACT
Membranes and enzymes are fundamental for all biological cells from the unicellular organisms to organisms a with higher level of evolution. Cell membranes are not only a physical boundary that separates the intracellular components from the extracellular environment, they also act as a selective barrier able to regulate what enters and exits the cell, thus facilitating the transport of materials needed for survival. The enzymes are found in all biological cells and are involved in almost all metabolic pathways. Their basic function is to increase the rate of reactions that would occur about a million times slower in their absence. Furthermore, they are selective for their substrates and speed up only a few reactions from among many possibilities.
