Question

Name the four types of cell junctions found in intestinal epithelial cells. Why don’t plants have as many types of junctions?

Answer 1

Cell Junctions of Intestinal Epithelial Cells

There are mainly four types of cell junctions in intestinal epithelial cells . They are

* Gap Junctions

* Desmosomes

* Adherens junctions

* Tight junctions

Gap Junctions

- It allows transfer of small molecules and ions from one cell to the another.

- gap juncton proteins are called Connexins, which form hexameric complexes called Connexons .

- Allows intercellular exchange of materials with small diameters - less than 1.5 nm.

- Absence of cytoskeletal components.

Desmosomes

- Demosomes or Macula adherens are disc shaped structures at the surface of cell

- They connect or link adjacent cells together through cytoskeletons.

- They contain members of Cadherin family called desmoglein and desmocollin.

- desmosomes provide firm adhesion among the cells.

Adherens Junctions

-Adherens junction or Zona Adhrerens are seen in membrane at the contact points between the cells.

- Role in cell migration, cell polarity, linking adjacent cells..

- Formed of proteins of Catenin and Cadherin families.

- They also strenghten and stabilize nearby tight junctions.

Tight Junctions

_ Tight Junction or Zonula Occludens Are made up of Claudin and Occludin protein families- 35 different proteins.

- It seals adjacent cells to one another, controling passage of molecules between them, are the functions.

- Have Actin filaments.

- Selective Paracellular transport of solutes.

Plants donot have as many of cell junctions. Animal cells have gap junctions but plant cells lack gap junctions. Instead plant cells have Plamodesmata. Plasmodesmata can be defined as tiny channels that connect plant cells together. And also Plant cells have cell walls which prevents easy communication with adjacent cells. Plasmodesmata is a solution to these issue.It allows transport of materials across cells.