Bacteria, the cell wall is composed of peptidoglycan. The cell walls ofarchaea have various compositions, and may be formed of glycoprotein S-layers, pseudopeptidoglycan, or polysaccharides. Fungi possess cell walls made of the N-acetylglucosamine polymer chitin.

**Chemical Composition of Cell Wall in Plants**

The cell wall is a rigid structure that surrounds the cell membrane of plant cells. It provides support, protection, and shape to the cells. The chemical composition of the cell wall in plants is complex and consists of various components.

**1. Cellulose:**
Cellulose is the primary component of the plant cell wall, accounting for about 30-50% of its composition. It is a linear polymer of glucose molecules and forms long, interconnected chains. Cellulose provides strength and rigidity to the cell wall, making it resistant to mechanical forces.

**2. Hemicellulose:**
Hemicellulose is another significant component of the plant cell wall, comprising around 20-35% of its composition. It is a branched polymer composed of various sugar molecules, such as glucose, xylose, mannose, and galactose. Hemicellulose acts as a filler and binds cellulose microfibrils together, contributing to the structural integrity of the cell wall.

**3. Pectin:**
Pectin makes up about 10-35% of the plant cell wall composition. It is a complex polysaccharide composed of galacturonic acid and other sugar molecules. Pectin contributes to the cell wall's flexibility and acts as a glue, binding adjacent cells together. It also plays a role in regulating cell adhesion and cell-to-cell communication.

**4. Proteins:**
Proteins constitute a small portion of the plant cell wall, ranging from 10-20%. They are involved in various functions, such as cell expansion, signaling, and defense mechanisms. Some proteins, called extensins, provide structural support, while others, like enzymes, participate in cell wall remodeling and modification.

**5. Lignin:**
Lignin is a complex polymer found in the secondary cell wall of some plant cells. It accounts for approximately 10-25% of the cell wall composition. Lignin provides rigidity and waterproofing properties to the cell wall, making it less susceptible to degradation and mechanical stress.

**Chemical Composition of Cell Wall in Fungi**

Fungal cell walls vary in composition compared to plant cell walls. Although there are similarities, the main component that distinguishes fungi is the presence of chitin.

**1. Chitin:**
Chitin is the primary component of fungal cell walls, comprising around 20-30% of its composition. It is a nitrogen-containing polysaccharide composed of N-acetylglucosamine units. Chitin provides strength and rigidity to the fungal cell wall, similar to cellulose in plants.

**2. Glucans:**
Glucans are another major component of fungal cell walls, accounting for about 20-60% of their composition. They are glucose polymers that can be classified into different types, such as β-glucans and α-glucans. Glucans contribute to the structural integrity of the fungal cell wall and are also involved in cell signaling and defense mechanisms.

**3. Mannans:**
Mannans are present in some fungi and make up a small portion of the cell wall composition. They are branched polysaccharides composed of mannose units. Mannans contribute to the cell wall's flexibility and may also play a role in cell adhesion and recognition.

**4. Proteins:**
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