Question

What are the three types of cell junctions known?

Answer 1

We need to know about cell junctions and their types. In mammals, cell junctions also known as intercellular bridges are multiprotein complexes that enable contact or adhesion between adjacent cells or between a cell and the extracellular matrix. Cell junctions also have a role in decreasing the amount of stress put on cells.

Complete answer:
Cell junctions work in conjunction with cell adhesion molecules and the extracellular matrix to keep animal cells together. Communication between nearby cells is enabled by specific protein complexes termed communicating (gap) junctions, which are found at cell junctions. They help keep epithelia's paracellular barrier intact and regulate paracellular trafficking. In epithelial tissues, cell connections are very numerous. The three types of cell junctions are described below:

1. Gap junction: It is a specific intercellular link that connects a variety of different animal cell types. They link the cytoplasm of two cells directly, allowing different chemicals, ions, and electrical impulses to flow directly between cells through a controlled gate.
2. Tight junctions: These are also known as occluding junctions or zonulae occludentes, are multiprotein junctional complexes whose main role is to close the paracellular route and prevent leakage of transported solutes and water. Tight junctions can also act as leaky routes for tiny cations, anions, or water by generating selective channels. Vertebrates are the only animals with tight connections.
3. Adherens junction: The cytoplasmic aspect of a cell junction is connected to the actin cytoskeleton. They can take the form of bands that encircle the cell (zonula adherens) or patches of extracellular matrix attachment (adhesion plaques). Adherens junctions in uterine epithelial cells disintegrate in a particular way to allow the blastocyst to pass between them.

Note:
Note that comparable communication channels in plants are known as plasmodesmata, while similar communication channels in fungus are known as septal pores. The structural tasks of cell connections are instead fulfilled by cell walls in multicellular plants. Plants have plasmodesmata, which are counterparts of communicative cell connections. Additionally, numerous cell adhesion molecules are involved in the formation of cell junctions. Selectins, cadherins, integrins, and the immunoglobulin superfamily are the four primary kinds.