Question

What is the difference between a plasma membrane and a cell wall?

Answer 1

The difference between plasma membrane and cell wall have been given below:

Cell membrane	Cell wall
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.
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.
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
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.
Cell membrane has receptors to receive signals from external chemicals.	Cell wall lacks any receptors.
In Bacteria, cell membrane gives rise to flagella (movement) and pilli (reproduction) like structures.	While cell wall facilitates flagella and pilli through small apertures.
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.
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.
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.
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.