What Makes Plant Cells Rigid?

Cell Wall

• The plant cell, unlike animal cells, has a rigid structure surrounding it, known as the cell wall. This structure is one of the main supporting aspects for a plant cell and is made up of a substance known as cellulose. The wall is rigid, but has small holes all the way around through which water and nutrients can pass in and out of the cell. Cell walls are also the reason that plants, unlike animals, cannot move around on their own. Animal cells, with their flexible membranes, can move more fluidly than solid, brick-like plant cells.

Microtubules

• Microtubules are found within the cell and have the principal task of moving substances around within the cell itself. These microtubules are fine tubes of about 25 nanometers in diameter that form dense internal highways. The density of these microtubules also helps to form the shape of the cell internally and add support to the cell's rigidity. The microscopic tubes are formed from a protein called tubulin.

Vacuoles

• Vacuoles are structures found in all cells that are primarily for the storage of waste or nutrients and are also part of the transport system within the cell. In animal cells, vacuoles are small, but in plants they are large, swollen sac-like organelles. Because they are larger within plant cells, the vacuoles also contribute to the rigidity of the cellular structure. The vacuole is full of a substance known as cell sap, which is bound inside a flexible membrane.

Xylem Tissue

• Certain types of plant cell are designed to eventually die and become almost solely structural. Xylem tissue cells, for example, become impregnated with a substance known as lignin, which causes the cell wall to thicken. The interior of the cell dies and becomes hollow to essentially form a tube suitable for water transport. The water is pulled up through these rigid cells from the roots and is distributed to the rest of the plant. Because these cells are basically dead, if they get broken or blocked, they cannot be repaired.