Summary
Tight junctions, desmosomes and gap junctions that seal, anchor or connect neighbouring animal cells.
In depth
Tight junctions seal neighbouring cells and prevent leakage, as in the lining of the gut and brain capillaries. Desmosomes are spot-like anchors linked to intermediate filaments, giving tissues like skin and heart strength. Gap junctions are channels made of connexins that let ions and small molecules pass directly.
In plants, plasmodesmata play the role of gap junctions.
Tight junctions are built from claudins and occludins and also separate the apical and basolateral membrane domains, so different transporters can occupy each side. Adherens junctions use cadherins linked to actin and bind cells together in a calcium-dependent way, and hemidesmosomes anchor cells to the basement membrane.
Gap junctions let the heart's cells beat as one unit by passing electrical current, and in the embryo they let cells share signals. Plasmodesmata, about 40 nm wide, link plant cytoplasm and permit transport of small molecules and even some viruses.
Example: the blood-brain barrier depends on very tight junctions between capillary endothelial cells, which restricts drug delivery to the brain.
Frequently asked questions
What is Cell Junctions?
Tight junctions, desmosomes and gap junctions that seal, anchor or connect neighbouring animal cells.
Which area of biology covers Cell Junctions, and how advanced is it?
Cell Junctions is one of the 52 topics in Cell Biology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Extracellular Matrix, Second Messengers, Cell Wall.
Can you give an example of Cell Junctions?
Gap junctions in cardiac muscle let electrical signals spread so the heart contracts in unison.
What should I learn before Cell Junctions?
Work through the Beginner topics in Cell Biology first, such as Cell Theory, Prokaryotic Cell, Eukaryotic Cell, then return to Cell Junctions. Intermediate topics assume the Beginner vocabulary.
What topics are related to Cell Junctions?
The closest topics to Cell Junctions are Extracellular Matrix, Second Messengers, Cell Wall, Cytoplasm. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Cell Junctions?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Cell Junctions. To practise the whole of Cell Biology, use the Cell Biology quiz.
How is Cell Junctions different from Extracellular Matrix?
Cell Junctions: Tight junctions, desmosomes and gap junctions that seal, anchor or connect neighbouring animal cells. Extracellular Matrix: A network of collagen and glycoproteins outside animal cells that provides support and cell signalling cues. Read both side by side and note what each one explains.
How should I study Cell Junctions step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Extracellular Matrix and explain the difference aloud. Finally, take the Cell Biology quiz and come back to this page for any question you miss.