Cell Wall vs. Cell Membrane
The cell wall is the outer most covering of the cell. The cell wall covers the cell membrane. The cell membrane is also known as the plasma membrane or plasma lemma. There is no other name for the cell wall. The cell membrane is present in almost all types of cells. The cell wall is present in bacteria, fungi, algae and plant cell. It is absent in an animal cell and protozoa. The cell membrane is a biological membrane, which is semi- permeable. It allows the passage of certain substances through them.
The function of the cell membrane is the same as that of the skin. It separates the components inside the cell from the outside. The cell membrane provides support to the cytoskeleton of the cell, gives shape to the cell, and helps in the formation of tissues by attaching the matrix found in the extra cellular. It allows the passage of a certain substance; it maintains the potential of the cell, helps in communication with other cells, and act as molecular signals. Protein receptors are present which receives signals from the other cells and the environment.
The function of the cell wall is to provide strength and rigidity to the cell. It protects the cell against mechanical forces. The function of the cell wall varies in different cells. In multi-cellular organism, it is responsible for its morphology. It prevents only large molecules from entering the cell and thereby, prevents toxicity to the cell whereas cell membrane prevents entry of smaller molecules. The cell wall also helps in retaining the water of the cell, thus a stable osmotic environment is created in the cell.
The composition of the cell wall varies in prokaryotic and eukaryotic cell. In prokaryotes, the cell wall is made up of peptidoglycans in the inner layer and lipoproteins, lipopolysaccharides in the outer layer. In eukaryotes, the primary cell wall is made up of cellulose, middle lamella is made up of pectins which are polysaccharides and secondary cell wall is made up of cellulose and lignin.
The cell membrane is made up of proteins, carbohydrates and lipids. Three types of lipids are found ‘“ glycolipids, phospholipids and steroids. The carbohydrate found in the cell membrane is glycoprotein. Other sugars like galactose and sialic acid is found. Three types of proteins are found ‘“ integral proteins, lipid anchored proteins, peripheral proteins. Trans-membrane protein is the other name for integral proteins.
The cell wall is elastic and controls turgidity. Plasma membrane is not elastic, but permeable. The cell wall is found in plant cells whereas cell membrane is found in animal cells.
SUMMARY:
1.Cell wall is found in plant cell and cell membrane is found in animal cells.
2.Cell membrane is covered by the cell wall which forms the outer most covering.
3.Cell wall is completely permeable whereas cell membrane is semi-permeable.
4.Cell wall is made up of cellulose and cell membrane is made up of lipids and proteins.
5.Cell membrane is also known as plasma lemma.