Biology · Structural Organisation in Animals · NEET
Tight junction stops substances from leaking across a tissue (a seal). Adhering junction cements neighbouring cells together to form a continuous sheet (mechanical anchoring). Gap junction connects the cytoplasm of adjacent cells and allows rapid transfer of ions and small molecules, so it is for communication. NCERT gives exactly these three functions for the three junctions.
Tight junction stops leakage; gap junction allows communication. This exact pair was asked in NEET 2021. Remember: 'Tight' feels like sealed and no gap for fluid to pass, while 'Gap' junction has channels that let ions and molecules pass, so cells can talk.
No. A tight junction seals the space between cells so fluid cannot pass. An adhering junction does not seal; it only glues or cements the cells so they stay together as a strong sheet. If a question says 'prevents leakage of fluid', pick tight junction, not adhering junction. This swap is the most common trap.
Intercalated discs are junctions, but they are found in cardiac muscle, not in the epithelial cell-junction list of tight, adhering and gap. In NEET 2021 a smooth muscle statement wrongly said 'communication among cells is by intercalated discs' — that is false, because intercalated discs belong to cardiac muscle. So do not mix intercalated discs into the epithelium junction trio.
NCERT describes tight, adhering and gap junctions in epithelial tissue. Epithelium covers surfaces and lines organs, so its cells need to seal (tight), stick (adhering) and communicate (gap). Knowing this location helps you answer chapter matching questions correctly.
Identify the types of cell junctions that help to stop the leakage of substances across a tissue and facilitate communication with neighbouring cells via rapid transfer of ions and molecules.
Match List I (cell junction) with List II (feature): (a) Tight junctions (b) Adhering junctions (c) Gap junctions (d) Synaptic junctions with (i) Cement neighbouring cells together to form a sheet (ii) Transmit information through chemicals to another cell (iii) Establish a barrier to prevent leakage of fluid across epithelial cells (iv) Cytoplasmic channels to facilitate communication between adjacent cells.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
NCERT mentions three in animal epithelial tissue: tight junctions, adhering junctions and gap junctions. In matching questions synaptic junctions may also appear, but the core epithelial trio is tight, adhering and gap.
Use 'Tight = Stop leak, Adhere = Stick, Gap = Gossip'. Tight seals against leakage, adhering sticks cells into a sheet, and gap lets cells communicate by passing ions and molecules.
Gap junctions. They are cytoplasmic channels that connect adjacent cells and allow rapid transfer of ions and small molecules, which is direct cell-to-cell communication.
Cell junctions are a small but high-return topic; they were asked in NEET 2019 and NEET 2021 as matching and direct-function questions. Learning three one-line functions can quickly earn a mark.
