How do tight junctions cling to the cell membranes of other cells and connect the other cells together?
(I answered this above). There are many different types of cell junctions which are expressed in all tissues, but particularly in epitheila, which have a range of specific roles in cell-cell and cell-matrix interactions. Tight junctions are formed by integral membrane proteins of adjacent cells binding strongly together. Within epithelia (such as the gut) tight junctions may act as diffusion barriers within the lipid bilayer to confine both transport proteins and also to block the backflow of glucose from the basal side of the epithelium into the gut lumen. See also a table showing a functional classification of cell junctions. The mitochondria and cloroplasts are said to have originated from a bacterium engulfed by a pre-eukaryotic cell.
