Cell Walls: What Do They Actually Do?

Every living organism is made up of cells. Some of these cells have walls, which play an important role in keeping the organism as a whole healthy and fully functioning system.

What Is a Cell Wall?
Not every cell has a cell wall. In fact, most animal cells don't. Instead, they are most commonly found in plants, bacteria, or fungi. In these cells, the wall is a barrier that wraps around it to give it strength, maintain its shape and determine what can come in and out of the cell. Animal cells have a different feature called the extracellular matrix that serves a similar function but is not as rigid as the cell wall. If you ever hear a crunch while chewing on some leafy greens, that sound is probably coming from breaking the cell walls, according to Khan Academy.

What Are They Made Of?
In order to fulfill the function of being strong and protective, the cell wall needs to be made up of a strong substance. The majority of cell walls are made of polysaccharides and differ from organism to organism.

Plant cell walls are mostly made of cellulose, which is a polysaccharide composed of glucose. There are other substances present but the majority is made from cellulose.

Cell walls in fungi are mostly made of chitin, which is a derivative of glucose. Chitin is similar to cellulose, but it's a little more crystalized. These cell walls also have other substances, whether that's glucose or proteins.

Bacteria cell walls are made of murein, which is made of both saccharides and amino acids. These are a little different to plant and fungi because they are single cell organisms. Their structure is going to need to reflect this difference in function.

What Do the Walls Do?
The cell wall keeps its structure and give it strength to resist pressure. One type of pressure that plant cells specifically face is called turgor. This is the force that the inner contents of the cell exert on its wall and help plants stay erect. In order to prevent bursting, the wall needs to be strong enough to withstand the pressure.

The cell wall also includes proteins, which depending on what they are made of, allow certain substances to pass through the wall. In plants, this regulates diffusion by determining how much carbon dioxide can come into the cell. In bacteria, this can affect how an antibiotic can kill it.

Communication through cells about temperature, nutrients, and anything else related to its survival happens through the cell wall. The plasmodesmata are small pores that allow signals to be passed from cell to cell in order to function correctly.

One other vital role the wall plays is limiting growth and reproduction. In order for cells to be most efficient, they are limited to a microscopic size. Once they grow and meet this size, it's time to reproduce. The cell wall has this information and sends an alert that it's getting too big and needs to divide and duplicate.

As you can see, cell walls are crucial when it comes to organisms and their functions. Without them, we wouldn't know where one cell ends and the other begins. Our plants and fungi would be liquid and bacteria would be unprotected.