Cell WallThe cell wall forms an inflexible
barrier that protects the cell, prevents too much intake of water, and gives it support. It is only found
in plant cells, prokaryotes, fungi, and some protists. The cell wall is made up of a thick, tough group of fibers, and
is much thicker than the plasma membrane. It is very porous and allows molecules to enter, but it does not select which
molecules can enter, unlike the plasma membrane.
The Extracellular Matrix
The Extracellular Matrix (ECM) are found in animal cells and help with the functions of
support, adhesion, movement, and regulation. The ECM is mostly made up of glycoproteins(proteins that covalently bond
with carbohydrates), however, the composition of the structure itself varies from cell to cell.
These connections are very common in epithelial tissue. These three intercellular
junctions in animals are vital to the function and structure of a cell.
- Tight Junctions are junctions that form a large belt around the cell. A tight junction fuses
neighboring cells together and forms a very tight seal that does not allow the leaking of extracellular fluid.
- Gap Junctions (communicating junctions) are junctions that provide a cytoplasmic connections between adjacent
cells. Salts, sugars, amino acids, and other small molecules pass through the pores in the gap junction.
(anchoring junctions) are junctions that form strong epithelial sheets by fastening cells together.