Which are important parts of cell membranes?
a. lipids
b. monomers
c. nucleic acids
d. monosaccharides

A. LIPIDS

Cell membranes contain membrane proteins that allows all the interaction that occurs within the cell. It makes the cell membrane selectively permeable because of its characteristics as being fluid or its fluidity which means to say that they can move freely within the lipid bilayer. The membrane proteins can also be stored in the lipid bilayer together with the enzymes. It cannot be denied that membrane proteins have a lot of functions based on its type. They can be integral proteins, peripheral proteins and lipid bound proteins. 

Are you asking about a street map usage  if so here is your answer  a street map for a very limited area could simply be a bit map or a .jpg image.  but a more general map would probably store the streets as vectors.  but you shouldn't assume that there is one way to do it