Though the cell walls in plants and bacteria share some similar functions, they are drastically different in roles and structure.

However, in plants, the structure is significantly different.

The plant cell wall is split into three layers: the middle lamella made of pectin used for cell-to-cell contact, the primary cell wall containing equal amounts of cellulose, hemicellulose, pectin which allows cell growth and lastly the second cell wall made of cellulose, hemicelluloses and lignin that protects the cell from pathogenic invasion and external damage from insects and well as facilitates the transport of water and minerals.

Given that the structures' components are so different, the functions of the cell walls in bacteria and plants also differ as well.

Both cell walls maintain the shape of the cell, prevent them from osmotic shock (rapid change in the water movement across the cell membrane) and aid in cell-to-cell contact but in bacterial cells, it aids in flagella attachment and pathogenic invasions and for plant cells, the cell wall facilitates water movement and provide additional support to the plant stems through the lignin present in the secondary cell wall.

A cell wall is "A rigid structure secreted external to the plasma membrane.

Cell walls are also found in algae, archaea, bacteria and fungi cells, giving them their inflexible structure.

They also play a role in the support of the cell, specifically the peptidoglycan layer, to control cell growth and prevent external damage as well as the overexpansion of the cell through osmotic pressure which can result in lysis.

Cell walls also help in smoothing out the binary fission process of cell reproduction and encourage cell-cell communication (they communicate via the plasmodesmata located on the cell wall).

Though they are not selectively permeable like cell membranes, they do prevent large, unwanted molecules such as viruses and pathogens from entering.

Pathology is a branch of medical science primarily concerning the cause, origin, and nature of the disease.

A bacterial capsule is "a layer of slime of variable composition that covers the surface of some bacteria with loosely associated capsules; encapsulated cells of pathogenic bacteria are usually more virulent than cells without capsules because the former are more resistant to phagocytic action."

The role of the bacterial capsule is to prevent the phagocytes from engulfing the cell, provide the bacteria with a virulence factor that makes it pathogenic, supply nutrients and water as well as protect the bacteria from harmful external forces such as physical pressures, noxious chemicals and bacteriophage attachment.

These functions and the highly-resistive nature of the capsule make it harder for the immune system to be rid of them quickly as the system's normal actions such as increasing the temperature of the organism markedly or flooding the community of bacteria with antibodies may not be as effective as other occasions hence a specific antibody with properties that break down the capsule has to be synthesized and used.

The food industry can have both positive and negative effects enacted on it by bacteria.

Naturally, bacteria, spoil food if left unrestricted and even much so with encapsulated bacteria.

The capsule allows for the bacteria to adhere themselves to the surface of the food, secreting a biofilm that allows for colonies to form rapidly while pulling nutrients from the food and decomposing it as the capsules protect them from external forces.

This doesn't mean there aren't proven benefits of bacterial capsules in the food industry such as flavour and texture enhancement and development of fermented foods through the rapid production of bacterial colonies.

Crystal violet (primary stain), Iodine solution/Gram's Iodine (mordant that fixes crystal violet to the cell wall), Decolorizer (e.g. ethanol) and Safranin (secondary stain)

As stated above a mordant aids in fixing the dye to the almost impermeable cell wall of the bacteria, making the colour of the stain more vivid and long-lasting.

Examples of such solutions are acids, bases, oil mordants, metallic mordants and iodine.

When iodine is used as a mordant it forms a complex with the dye in the cell; if replaced with an oxidizing agent there is a higher chance of a gram-positive bacteria to display a gram-negative colour as the protein structures in the peptidoglycan will unfold and make it more permeable to alcohol (bursting in contact) and become stained with the counter, Safarin.

Due to the size of the peptidoglycan layer of the cell walls, the colours will be markedly different during decolourization.

Bacteria that are said to be gram-negative have a thin peptidoglycan layer around 2-7 nm (10-20% peptidoglycan); this low murein content makes the cell less susceptible to drying out but more so to the stain leaking out of the layer.

Another reason for the leaking of the stain from the cell walls is the lack of teichoic acids leaving the cell wall positively charged which repels the dye.

On the other hand, Gram-positive bacteria have a very thick peptidoglycan layer 20-80 nm thick with a 70-90% murein content, making it easier for the dye to be retained in the cell wall along with the presence of teichoic acids which provide the cell wall with an overall negative charge which attracts the positively charged basic dye.

Such differences in the composition of their cell walls require that a separate approach to gram staining be applied to each, hence it is possible to tell the difference between the two.

The typical procedure is to have the slides with the sample stained with a basic dye of crystal violet, iodine and then destained with alcohol and then counterstained with safranin.

This results in gram-positive bacteria being stained purple, while gram-negative bacteria are stained pink as the gram-positive bacteria can retain the dye better, even when rinsed with alcohol, than the gram-negative species.

Due to the fast leeching of the stain, the alcohol is used to dehydrate and dissolve the lipids of the outer cell membrane in the gram-negative bacteria so the crystal violet dye-iodine complex can leak out making the counterstain of safranin more visible on the cell wall of the bacteria.