Which of the following makes it necessary for animal cells, although they have no cell walls, to have intercellular junctions?
A) Cell membranes do not distinguish the types of ions and molecules passing through them.
B) Large molecules, such as proteins and RNA molecules, do not readily get through one, much less two, adjacent cell membranes.
C) Cell-to-cell communication requires physical attachment of one cell to another.
D) Maintenance of tissue integrity and barriers to fluid leakage requires cells to adhere tightly to one another.
E) The relative shapelessness of animal cells requires a mechanism for keeping the cells aligned.

Question

Quizplus · Accepted Answer

Animal cells lack the rigid cell wall that provides structural support to plant cells. Intercellular junctions, such as tight junctions, desmosomes, and gap junctions, are necessary for animal cells to adhere tightly to one another and maintain tissue integrity. This is important for creating barriers to fluid leakage, for example in the lining of the digestive tract, as well as for supporting the shape and function of tissues such as muscle and skin. Option A is incorrect because cell membranes do selectively regulate the movement of ions and molecules. Option B is incorrect because small molecules can readily pass through adjacent cell membranes via diffusion. Option C may be a function of intercellular junctions, but it is not the primary reason for their necessity. Option E does not accurately describe the physical properties of animal cells.

Which of the Following Makes It Necessary for Animal Cells