We can't see them, we can't touch them and we can't taste them, but they have a collective mass greater than almost all other organisms, they cover surfaces of all kinds in all environments, and by the products of their metabolisms we may enhance the taste of food or suffer the danger of deadly toxins. They are the myriad microbes we call bacteria, and are classified as the simplest of types, prokaryotes.
Recent evidence suggests differences in evolutionary relationships among prokaryotes.
The success of prokaryotes is based on diverse adaptations of form and function. Cell Surface- Protection from hypotonic media by cell wall. Some bacteria have pili or stalks , surface appendages that function in adhesion and genetic exchange during bacterial conjugation . Many species of bacteria are motile , that is capable of directed movement. Three mechanisms involved 1.