Biology / Unit 2 Bio 0311 short lesson, about 20 seconds
Tight Junctions
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The idea
A tight junction is a watertight seal, built mainly from claudin and occludin proteins, that holds two adjacent animal cells tightly together.
In practice
Tight junctions between cells lining the urinary bladder keep urine from leaking into surrounding tissue.
Where people slip
A tight junction seals space between cells; students often mistake it for a channel like the gap junction, which instead lets molecules pass through.
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