What would happen if the nucleus was permeable to most substances?

Answer 1

Most likey it would stop being a nucleus, or function as a nucleus. The nucleus of a cell has a protective shell called a nuclear envelope or nucleolemma. It is a double layered structure as opposed to the single layer of the cell membrane, or plasma membrane. If you imagine the cell membrane to be like a chain-link fence around the yard of a property, then the walls, windows, and doors of the house would be the nuclear membrane and the inside of the house, where you live, would be the inside of the nucleus. No imagine if all your windows and doors stayed open all the time and had no screen. Pretty soon you wouldn't be able to tell what belonged inside your house or in the yard, or even down the street. There would not only be trash inside the house, but all the valuable stuff you were protecting would very likely find its way outside, and even down the block. So you are probably getting the idea. Sort of like the saying, it's the cloths that make the man, or the walls that define a house. Well, same for biological structures, they are defined by what holds them where they are, and keeps things that are not them, away and outside of where they are.