Cell wall

Definition

A cell wall is a rigid outer layer found in cells of plants, fungi, bacteria, algae, and some archaea. It provides structural support and protection, and helps maintain cell shape.

5 Must Know Facts For Your Next Test

1. Prokaryotic cell walls contain peptidoglycan, a polymer that provides strength and rigidity.
2. Plant cell walls are primarily composed of cellulose, hemicellulose, and lignin.
3. Fungal cell walls are made of chitin, which is also found in the exoskeletons of arthropods.
4. The Gram staining technique differentiates bacteria based on their cell wall composition: Gram-positive bacteria have thick peptidoglycan layers, while Gram-negative bacteria have thin peptidoglycan layers and an outer membrane.
5. Cell walls in eukaryotic algae are usually composed of polysaccharides like alginate or agar.

Review Questions

• What are the main components of the plant cell wall?
• How does the composition of bacterial cell walls differ between Gram-positive and Gram-negative bacteria?
• What polymer is commonly found in fungal cell walls?

Related terms

Peptidoglycan:

A polymer that forms a mesh-like layer outside the plasma membrane of most bacteria.

Cell Membrane:

A biological membrane that separates the interior of all cells from the outside environment.

Gram Staining:

A method of staining used to differentiate bacterial species into two groups based on their cell wall composition.