In order for a cell to function, chemical signals and other types of molecules need to get from one area of the cell to another. mRNA needs to get from where it is created to DNA, and then from DNA to the ribosomes and other locations of the cell. Chemical signals need to get from one areas of the cell to another in order to keep the signaling pathways functioning. Sugars need to get from outside the cell to the inside, while waste products need to get back out. But how do they get around? Is it simple diffusion with some "pumps" or "gates" to get in or out of certain areas of the cell? Or are there other factors working here? I know things like vacuoles exist, but then how does those get around? I'd appreciate any information and links. Even suggestions for books. Thanks in advance.