3.4.4 Animal Cell Junctions Flashcards
cell junctions
- regions where cells are physically side by side. Junctions permit cell communication
tight junctions
- function as seals between two cell-lined compartments, preventing the flow of fluids through the extracellular space.. Tight junctions are advantageous when material critically needs to enter the cell without leakage.
- They are characterized by a complete lack of
intercellular space
desmosomes
- localized points of tight adhesion between adjacent cells of a tissue. The structures provide adhesion and enables cells to function as a single unit. The binding
proteins consist mainly of keratin fibers. - The average intermembrane space is between 25-35 nanometers (nm).
gap junctions
- possess some intercellular space, thus enabling the movement of material from cell to cell or into the
environment. Interestingly, cancer cells lack gap junctions, disabling the cells from communication. - The average intermembrane space is 2-3 nanometers (nm).
Junctions that hold animal cells together without leaving intercellular space
- tight junctions.
Junctions that permit the transfer of water, ions and molecules between cells are
- gap junctions.
Which statement about animal cell junctions is not true?
a. Tight junctions serve as barriers to the passage of extracellular fluid between cells.
b. Desmosomes allow cells to adhere tightly to one another at specific points.
c. Gap junctions prevent communication between cells.
d. The fibers associated with desmosomes are made of proteins.
- c. Gap junctions prevent communication between cells.
List the types of animal cell junctions in order of decreasing distance between cells.
- desmosome, gap junction, tight junction
True or false?
A polarity may exist in cells with tight junctions because proteins cannot migrate around tight junctions.
- true
