What are large, complex structures that form slowly but generate very strong and durable connections on the cell surface?

Large, complex structures that form slowly and generate strong and durable connections on the cell surface are indeed best described as cell junctions. These specialized structures facilitate communication and adhesion between adjacent cells, contributing to tissue integrity and function.

Cell junctions include various types such as tight junctions, adherens junctions, desmosomes, and gap junctions, each serving distinct roles in maintaining tissue architecture. They are essential in regulating molecular trafficking between cells and helping to establish barriers, such as those found in epithelial tissue. Their complexity and the way they are assembled contribute to the strength and durability of the connections they create.

In contrast, cell adhesion molecules are proteins that mediate adhesion between cells and can be involved in transient interactions, rather than the durable connections characteristic of cell junctions. Substrate adhesion molecules typically refer to proteins that help cells adhere to extracellular matrices or surfaces, rather than directly to other cells. The term "cell adhesion" is a broader concept that encompasses various types of adhesion but does not specifically highlight the complex structural nature and function that cell junctions exhibit.

Thus, the specific definition of cell junctions aligns closely with the description of large, complex structures that form strong connections on cell surfaces.