Cell membrane and cell wall are both part of the cell.
But of them cell membrane is an organelle having life.
While, the cell wall is a non-living structure. Both of them are present at the boundaries of the cells.
Their common role is to give protection to the whole cell and other organelles in the cell. Further both of them together form the cytoplasmic bridges.
These cytoplasmic bridges help in inter-cell communication and transfer.
Also both of them are involved partly in cell division and exist from birth to death of the cell. But there are many difference between Cell Membrane and Cell Wall which we will see in a table below.
Difference between Cell Wall and Cell Membrane.
Before we go into details, check the two cells below. One is of plant cell and other is animal cell. Plant cell has cell wall while animal cell has not wall. Click the images below for enlarged view.
|Sl.No||Cell membrane||Cell wall|
|1||Cell membrane is present in all types of cells. i.e human, animal, plant, bacterial etc.||Cell wall is Present in only plant cells and bacterial cells.|
|2||Cell membrane is an organelle of the cell. And is outermost cover in animals and humans. It provides shape to cell which is flexible.||Cell wall is the outer non-living cover of the cell but not an organelle. It encloses cell membrane. It also provides a fixed shape.|
|3||It is a lipid bilayer. And is made of lipo-proteins.||This is made of pectin, chitin, lignin etc. In bacteria it is made of glyco-proteins, glyco-lipds|
|4||This has the ability to contract. It is flexible to change the shape as needed.||Cell wall is rigid with fixed shape. Any pressure application can break the wall.|
|5||Cell membrane has receptors to receive signals from external chemicals.||Cell wall lacks any receptors.|
|6||In Bacteria, cell membrane gives rise to flagella (movement) and pilli (reproduction) like structures.||While cell wall facilitates flagella and pilli through small apertures.|
|7||It is of the same thickness in the whole life time of the organism.||The wall grows in thickness over time. Further, it occupies whole cell in plant as the cell ages and dies.|
|8||The membrane is permeable and controls the movement of substance into and outside the cell. That is, it can allow water and other substance to pass through selectively.||The cell wall is semi-permeable. It allows passage of substances with size of 30-60kD.|
|9||Cell membrane has functions like permeability, signal reception, motility (amoeba), conduction (nerve cell), cell division, sexual reproduction etc.||Cell walls only function is protection from external harsh environment.|
|10||Cell membrane requires nutrition from cell. So it shrinks during fast and drought conditions.||While cell wall is mere deposit of substances. So it does not need nutrition but mere deposition in case of damage.|
The presence of cell wall makes a huge difference in targeting bacteria in human and animal infections. This is used as a target to kill them specifically by use of anti-biotics without damage to animal cells. As per taxonomy and evolution point of view, presence of cell wall is a primitive aspect.
With advancement of life, the cell wall has become obsolete.
Check out The Functions of Cell wall in plant cell.
But the other argument is for plants cell wall is essential. Because, since they are non-motile, they need cell wall to protect themselves from harsh condition. But animals on other hand can run away from those conditions or make alternatives for protection like hiding in safety or covering themselves. So they may not need cell wall. Also in the most primitive organism like bacteria, there is further protection on the cell wall in the form of capsule. This is also an additional layer developed by them in time of drought conditions.
So we can conclude that cell wall is a mere protection layer while the membrane is both a protective, structural as well as a physiological requirement.