The cell membrane would be a locked door (for example) so that ONLY the people with a key can get in and the people without a key would not be able to get in.
if a cell membrane was in a city what would it be?
The Cell Wall would be the wall surrounding the city (no equivalent in modern cities). In comparison, the membrane would be the city border patrol. Nobody is going to get past the cell wall, but once they do whether or not they enter the cell (city) is determined by the membrane and its proteins (border patrol)
I think the border of the city or like a fence or wall would be the best one I can think of.
The cell membrane - without which cytoplasm is meaningless - serves to contain cytoplasm just as a wall would contain a city.
what would best represent a cell membrane in an animalcell what would best represent a cell membrane in an animalcell
The Cell Membrane
The plasma membrane could be considered the gate to the city. :)
in a plant cell the cell membrane would be the plaster on the walls. in an animal cell the cell membrane would be the walls, doors and windows.
The fenders, roof, hood and truck lid would be like a cell membrane.
jail
The casing to the computer or the covering for the computer would be similar to a cell membrane.
A good item for a cell membrane would be a thin plastic or cardboard