Bacterial cell wall | Its Structure and Function
A bacteria cell wall is an important structure for the life of bacteria.
It is present just above the cell membrane and acts as the outer most cover of the cell.
Because of this cell wall, bacteria can survive even the harshest environmental conditions like drought, heat, chemical exposure, pressure, etc.
Thus cell wall is an important structure which makes it immortal.
For the man, it is an essential target in health care to cure bacterial infections.
The cell wall is a characteristic feature similar to a plant. So, some scientists even classify it under the plant kingdom. But unlike plants, the contents of the wall are entirely different.
The bacterial cell wall is tough, rigid with a specific shape.
The bacterial cell wall structure:
Structure of the bacterial cell wall is classified into two types. The one present in gram-positive bacteria and the other present in gram-negative bacteria. Below you can see the images for structures of two cell walls.
Gram-positive bacteria cell wall:
This cell wall is very rigid and is mainly made of peptidoglycan. Peptidoglycan is a combination of protein and carbohydrate molecules.
Because of this high amount of peptidoglycan layer, the bacteria show blue color when stained with gram stain. The layer does not take up the saffron color of stain, unlike gram-negative bacteria. This difference in cell wall structure makes the bacteria susceptible to antibiotics which act on the cell wall.
Gram Negative bacteria cell wall:
This cell wall is entirely different from the one above. The amount of peptidoglycan layer is very much low.
Besides it also has lipoproteins, lipopolysaccharides, phospholipids teichoic acid, etc. This cell wall when stained with grams stain, it attains saffron color. The lipopolysaccharide layer holds the saffron dye in the stain and is responsible for the color.
Functions of bacteria cell wall:
- It helps to provide a fixed shape to the cell.
- It facilitates movement of gases and water into and outside the cell.
- It prevents from the cell getting dried.
- It protects from chemicals and other harsh condition of the environment. Hence we use heat sterilization to kill bacteria.
- The outer most layer also called S-layer helps the bacteria to escape from phagocytosis by host immune cells.
Because of the cell wall presence, humans target them by giving drugs (antibiotics) which destroy cell wall. Since human cells don’t have a wall, they are unaffected. Similarly, due to the difference in gram +ve and gram -ve bacteria, an antibiotic with specificity to one type of bacteria can be given. Thus the presence of bacteria is good for bacteria but also provides a safe option for human health care.