Question

Observe the figure of plasma membrane exhibiting cell junctions of various epithelial tissue and match from a to c with respective features.
1. Protein complexes that occur at cell - cell junctions in epithelial and endothelial tissues.
2. Gap junction or nexus are separated by a distance of 30-50 $\mathring{A}$ by the number of pipe-like structures that extend from the cytosol of one cell to other by cylindrical proteins called connexons.
3. Tight junction form fluid tight seals between cells.

• A. 1 - a, 2 - c, 3 - b
• B. 1 - b, 2 - a, 3 - c
• C. 1 - a, 2 - b, 3 - c
• D. None of the above

Answer 1

The correct option is A 1 - a, 2 - c, 3 - b

1. A cell junction is a structure present in the tissues of the multicellular organisms. It is made up of multiprotein complex and provides the communicating junction between two adjacent cell. It is mainly present between the cell of epithelial and endothelial tissues.

2. Gap junctions are a specialized intercellular connection between a multitude of animal cell-types by the direct connection of cytoplasm by the proteins called as connexon and allows the molecules to pass through a regulated gate between cells.

3. Tight junctions, also known as occluding junctions or zonulae occludentes are the closely associated areas of two cells whose membranes join together forming a virtually impermeable barrier to fluid.

Thus, the correct answer is option A.