Because plant and animals are multicelled then it would make sense that the cells that make up these eukaryotes would have a mechanism for cell-to-cell communication whereas, in single-celled eukaryotes there is no need for this capability. In animal cells this is called "gap junctions, tight junctions, or desmosomes" and in plant cells this is called "plasmodesmata.” The plasmodesmata allows water and small molecules to pass from cell to cell. The gap junction acts the same as the plasmodesmata but is for animal cells. The tight junction allows tight seals as the name implies so we have cells such as skin that do not allow materials such as water to pass through. Lastly, desmosomes act like anchors so any cells that need to be closely connected to neighboring cells yet still need the ability to move freely will be attached via desmosomes. We see desmosomes within muscle cells.
Work Step by Step
See figure 6.29 and 6. 30