How Does Adhesion Affect Living Organisms

Cells interact with and attach to the neighboring cells through adhesion. Cell adhesion occurs through specialized molecules, which attach cells to the extracellular matrix. Cell adhesion is maintained by adherens junctions, tight junctions, etc. Cells are attached to each other by cell adhesions. In multicellular organisms, this helps the formation of tissues. Cell adhesion also permits cell communication by facilitating the cell signaling pathways. In addition, cell adhesion plays a major role during the development as well.

Key Areas Covered

1. What is Adhesion
     – Definition, Cell-Adhesion Molecules, Types of Junctions
2. How Does Adhesion Affect Living Organisms
     – Role of Cell Adhesion

Key Terms: Cell Adhesion, Cell-Adhesion Molecules, Intercellular Communication, Morphogenesis, Tissues

What is Adhesion

Cell adhesion is the process by which cells form contact with each other. Special protein complexes are involved in the cell adhesion. Cell adhesion can occur in two ways either through direct contact or indirect contact. In indirect contact, cells attach to their extracellular matrix. Extracellular matrix is the gel-like matrix formed by molecules that are released by cells. The main function of cell adhesion is linking cells in different ways to facilitate signal transduction.

The molecules involved in the cell adhesion are called cell-adhesion molecules. The four families of cell-adhesion molecules are integrins, cadherins, selectins, and immunoglobulins (Ig). The binding between cell-adhesion molecules allows the formation of junctions such as adherens junctions, tight junctions, gap junctions, and signal relying junctions.

1. Adherens junctions – Adherans junctions strengthen the contact between cells.
2. Tight junctions – Tight junctions seal the gaps between cells.
3. Gap junctions – Gap junctions link the cytoplasm of the adjacent cells.
4. Signal-relying junctions – Signal-relying junctions occur in the synapses of the nervous system.

Types of cell junctions are shown in figure 1.

Figure 1: Cell Junctions

How Does Adhesion Affect Living Organisms

The major function of cell adhesions is linking cells together. Hence, cell adhesion plays a major role in multicellular organisms.

1. Formation of tissues – Cell adhesions allow a group of cells to be linked together. Cells that are specialized to perform a particular function can be grouped together by cell adhesions. Hence, the cells in a tissue may function as a unit.
2. Intercellular Communication – Cell adhesions permit cell signaling among cells of a particular tissue by passing signal molecules from one cell to another through cell junctions.
3. Morphogenesis – Cell adhesion plays a critical role in morphogenesis. Cell adhesion allows the migration of signal molecules and other cytoplasmic determinants from one cell to another.

Conclusion

Cell adhesion is the attachment of cells together. This permits the cells in a tissue to function as a unit. Cell adhesions also allow the signal molecules to migrate among the cells in the tissue. Cell adhesion also plays a major role in morphogenesis.

Reference:

1. Alberts, Bruce. “Cell-Cell Adhesion.” Molecular Biology of the Cell. 4th Edition., U.S. National Library of Medicine, 1 Jan. 1970, Available here.

Image Courtesy:

1. “Cell junctions types shown on epithelial cells including cell-cell and cell-matrix junctions”