Definition of a Tangent Plane We all have and intuitive idea of what the tangent plane to a point on a given surface should be. It is the plane that goes through that point and that it is tangent to the surface at that point. Suppose. z = f(x,y) is a smooth surface above the xy-plane (see the picture below).
The two prokaryotic domains (or empires),  Bacteria  (or  Eubacteria ) and  Archaea  (or  Archaeobacteria ), are subdivided into 35 phyla (or divisions): 30 phyla in the domain  Bacteria , and 5 phyla in the domain  Archaea .
What is the cell structure of eubacteria and archaebacteria? A: Eubacteria and archaebacteria have a wide variety of shapes. However, these cell types have no membrane-bound organelles, they do not organize their DNA into a nucleus, and they are contained by cell membranes protected by cell walls. Both are relatively simple in structure, so most of their differences are chemical, not structural.