ten FACTS ON
CELL WALLS by Philip McIntosh
Want to get inside a plant cell ? You ’ ll have to go through the cell wall first .
A CELL WALL can be thought of as a stiff yet flexible outer covering that surrounds the cell membrane to provide protection and support .
NOT EVERY CELL has a cell wall . This feature is found only in plants , fungi , and bacteria .
CELL WALLS ARE quite famous in the history of biology . Robert Hooke observed the walls of cork cells under his microscope in 1665 , which was the first step in the development of the cell theory ( all living things are composed of cells ).
THE MAIN COMPONENT of plant cell walls is the polysaccharide cellulose , which is made of long chains of glucose molecules .
SINCE PLANTS ARE so abundant , and they all have cell walls , there is more cellulose on Earth than any other macromolecule .
ALONG WITH CELLULOSE , other cell wall constituents include , lignin , pectin , hemicellulose , and some associated extracellular proteins .
PLANT CELLS MAINTAIN cytoplasmic connections with each other through tiny channels in their cell walls called plasmodesmata .
AS PLANT CELLS absorb water , the central vacuole expands , pressing the contents of the cytoplasm against the cell wall creating turgor pressure which keeps the plant erect .
UNDER DROUGHT CONDITIONS , water leaves the cells , causing wilting . However , the cell walls maintain the plant ’ s overall structure and allow it to return to normal form when water is restored .
THE CELL WALL is not like a solid assemblage of bricks and mortar . It consists of distinct fibrilous layers with spaces for small molecules to pass through . For this reason , some researchers prefer the term “ extracellular matrix .”
90 Maximum Yield