Cell Junctions MCQ - Practice Questions & Answers

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The function of the gap junction is to :

facilitate communication between adjoining cells by connecting the cytoplasm for rapid transfer of ions, small molecules and some large molecules.

separate two cells from each other.

stop substance from leaking across a tissue.

performing cementing to keep neighbouring cells together.

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Concepts Covered - 1

Specialised Junctions between Epithelial Cells

Epithelial cells are connected by the intercellular junctions which are as follows
1. Tight junctions: Plasma membranes of two epithelial cells in the apical parts are fused together to form tight junctions. These check the flow of materials between the cells.
2. Gap junctions: These are responsible for the exchange of chemicals between adjacent cells.
3. Adhering junctions: These act like cement to keep neighbouring cells together. These are of three types
(a). Zonula adherens: These are dense plaque-like structure towards the cytoplasmic side of each plasma membrane from which fine microfilaments are extended into the cytoplasm.
(b). Desmosomes: These are also plaque-like thicker and stronger junctions with microfilaments of keratin protein. These microfilaments are called tonofibrils. This anchor the cells.
(c). Hemidesmosome: These are similar to desmosomes, but the thickening of the cell membrane is seen on one side only. These join epithelial cells to the basal lamina.