Advanced Placement (AP) Biology Practice Exam

What is the name of the cell junction that allows communication between animal cells?

1. Plasmodesmata

2. Adherens junctions

3. Tight junction

4. Gap junction

The correct answer is: Gap junction

The cell junction that facilitates communication between animal cells is known as a gap junction. These specialized structures allow for the direct transfer of ions, small molecules, and signals between adjacent cells, enabling coordinated activities and responses. Gap junctions are composed of connexins, which form channels that bridge the gap between neighboring cell membranes. This is crucial for numerous physiological processes, including cardiac muscle contraction and neural signaling, where rapid communication is essential for coordinated function. In contrast, plasmodesmata are structures found in plant cells that also allow communication, but they do not exist in animal cells. Adherens junctions and tight junctions serve different purposes; adherens junctions are involved in cell-cell adhesion and structural integrity, while tight junctions create barriers to prevent the leakage of substances between cells. Thus, their functions are not specifically aligned with intercellular communication like those of gap junctions.