Cell Wall

Introduction

One of the many features that distinguish plant cells from animal cells is the cell wall. 

The cell wall is commonly regarded as an unresponsive system that meets primarily mechanical and structural functions. However, it consistently performs many essential tasks for plant life.  

A cell is the fundamental part of an organism that comprises a set of that organism’s elements. The cell wall is a plant cell’s defensive, semi-permeable outermost layer. The cell wall’s primary function is to provide support and rigidity to the cell and filter molecules that enter and exit the cell. 

Meaning of the Cell Wall

A cell wall is a compositional structure covering some cells external to the cell membrane. It can be hard, adaptive and even restrictive at times. It provides additional stability and protection to the cell while also acting as a filtering framework. 

Functions of Cell Wall

The functions of the cell wall are as follows:

• The cell wall offers complete protection for a living cell from its surroundings. It acts as a buffer between a cell and its outer environment
• It provides a highly absorbent channel for the circulation and distribution of water, minerals and other tiny nutritional molecules
• It serves as a restrictive component from which leaves and stems can develop
• The cell wall acts as a storage site for signal proteins & regulates the molecules that detect the existence of pathogenic microbes and contaminants

Characteristics of Cell Wall

The cell wall is present in prokaryotes, microorganisms, unicellular organisms, molds and bacteria. 

Bacterial cell walls are defined by the existence of peptidoglycan, whereas Archaea cell walls are void of this chemical. Algal cell walls are equivalent to plant cell walls and several include certain polysaccharides that aid in the classification system. Unlike plant and algae cell walls, fungal cell walls are composed entirely of chitin.  

Properties of The Cell Wall

The cell wall is made up of two layers: the middle layer called lamella and the primary cell wall. A few types of cells develop an additional layer known as the secondary wall. The middle layer, which is lamella acts as a concreting layer between adjoining primary cell walls. 

The primary wall contains cellulose and is established by splitting and growing cells. Primary walls seem to be thinner and far less rigid in developing cells. 

The cell walls expand throughout the cell development. A fully developed plant cell may hold its primary cell wall, thicken it or deposit an extra, rigid layer of various compositions, referred to as the secondary cell wall.

Secondary cell walls provide most of the plant’s support structure and material performance features. Unlike thick secondary walls, which have lasting rigidity and a massive amount of bearing ability, slender primary walls can only end up serving as a functional, supportive role when the vacuoles inside the cell are full of water. 

At this point, the cell wall experiences turgor pressure. The tightening of the primary walls induced by turgor is comparable to the strength and stiffness of the sides of compressed air tires. When the flowers and leaves wilt, it is followed by a decrease in turgor pressure, which leads to a loss of water from the plant cells.

Components of The Cell Wall

The comprehensive chemical structure and physical arrangement of primary and secondary wall layers are different. However, their basic structure remains the same. 

The cell wall is made up of cellulose fibres with high stiffness integrated into a surface mixture of polysaccharides and systemic glycoproteins. The series of cellulose microfibrils and inter glycans are composed in a pectin polysaccharides matrix that is strongly linked. Secondary cell walls also contain lignin.

The Cell Wall of Bacteria

All the bacterial forms do not have a cell wall. However, it is also worth noting that 90% of the bacteria have cell walls. 

Most bacterial organisms have a cell wall outside the cell membrane. It is an added layer that, due to its semi-rigid framework, normally includes some strength that the cell membrane appears to lack.

Bacteria customarily have one of the following two types of cell walls:

• A gram-positive cell wall 
• A gram-negative cell wall 

The bacterial cell wall is made up of peptidoglycan. Peptidoglycan, also known as murein, is a component found in both gram-positive and gram-negative cell walls. The former have a thicker layer of murein than the latter. Aside from being present in the cell walls of bacteria, this substance has not been discovered anywhere on Earth. 

Both types of bacterial cell walls contain added ingredients. This aspect makes the bacterial cell wall a complicated framework in a broad sense, especially compared to eukaryotic microbes’ cell walls. 

Eukaryotic microbe cell walls have a single active component, such as cellulose in algal cell walls of chitin in fungal cell walls. (The cell wall in fungi is located externally on the plasma membrane.)

Functions of Cell Wall- 

• It gives the cell structure
• It keeps osmotic bursting at bay
• It shields the protoplasm from mechanical damage
• It regulates the transport of molecules, water and proteins within the cell and between cells
• It serves as a food storage container
• It maintains the cell’s shape
• It controls the growth of cells
• It provides anti-pathogen protection
• It protects the cell and keeps it from being physically destroyed

Presence of Cell Wall

The relatively rigid layer, the cell wall, surrounds the cell from outside the plasma/cell membrane. It offers extra security and protection. 

The cell wall is present in single-celled organisms. Thus, it is present in Bacteria, archaebacteria, microbes, fungi, germs, yeasts, microorganisms, plants and algae. 

Animals and the majority of other protozoans have cell membranes. These structures, however, are not enveloped by cell walls. 

Conclusion 

We have explored several topics through the study material notes on cell walls, including their components and properties, the cell wall of bacteria, organisms that develop cell walls and other related topics. 

We also discussed some key points of what the cell wall is made up of & what the bacterial cell wall is made up of in detail.