Final answer:
The distance between the plasma membranes of two cells connected by a desmosome is roughly 20-30 nanometers. Desmosomes provide tensile strength, acting like rivets and binding cells together with cadherin proteins to the intermediate filaments of the cytoskeleton.
Step-by-step explanation:
The distance between the plasma membrane of two cells connected by the desmosome is approximately 20-30 nanometers (nm).
Desmosomes are specialized cell-cell interaction structures found only in animal cells. These structures work like rivets, providing tensile strength to tissues that undergo severe stretching, such as skin, heart, and muscles. Desmosomes consist of cadherin proteins that extend from the plasma membrane of one cell to another, bridging the intercellular space and anchoring to the intermediate filaments of the cytoskeleton. The plaque proteins inside the cell bind to these cadherins and to intermediate filaments like keratin, forming a continuous adhesive strip or spot around the cell.
This network endows the tissue with mechanical integrity and resistance to shearing forces. Gap junctions, which enable chemical communication through ion and molecule movement between cells, and tight junctions, which create watertight seals, are different from desmosomes in function and structure.