Difference between Cell Membrane and Plasma Membrane

Both Cell membrane and plasma membrane are integral parts of cell structure. These two components are the protective layers that protect the cell from external shocks. 

The cell organelles, along with all the ions and molecules, are surrounded by these two layers. Often these two terms are used synonymously, but the difference between cell membrane and plasma membrane is substantial. 

What is Plasma Membrane?

Plasma membrane is a kind of phospholipid membrane, present in all cells. It protects the protoplasm of a cell from outer hazards and checks the movements of molecules in and out of a cell. 

State true/false: Two cells can form a continuous common plasma membrane.

Ans. True. 

What is Cell Membrane?

Cell membrane is a thin multifaceted layer that acts as a barrier between the inner parts of a cell and the other part. It protects the cytoplasm of a cell and also provides shape to a cell. This particular membrane is a part of all cells, animals and plants. 

However, in plant cells, algae and fungi, a cell wall is present and it envelopes the membrane. It is a kind of plasma membrane. 

Once you know the basic concepts of these membranes, it will be easier for you to differentiate between plasma membrane and cell wall. Let’s begin!

 Plasma Membrane vs Cell Wall

There are a few difference between plasma membrane and cell wall. Some of them are discussed below. 

  1. Definition

Plasma Membrane is a thin layer, sized 5-10 nm, secures the interior of a cell from extracellular space. 

Cell wall is the rigid outermost layer of a cell, sized 4-20 um. It supports the cell to continue its inner mechanism. In some plants, it consists of three layers.  

  1. Presence 

Plasma membrane is present in all kinds of cells. Cell wall is present exclusively in plant, bacteria, fungi, algae cells. 

  1. Structure

Plasma membrane is thin and is visible only under an electron microscope. The hard Cell wall is visible through a light microscope. 

  1. Composition 

While plasma membrane is made up of lipids, proteins and carbohydrate, Cell wall consists of chitin (fungi), cellulose (plants) and peptidoglycan (bacteria)

  1. Type of organism 

Cell wall is non-living and inactive, whereas plasma membrane is living and metabolically active. 

  1. Receptors

Another difference between plasma membrane and cell wall is that the former contains receptors; however; the latter one does not contain any receptors. 

  1. Nutrition

The former one requires nutrition to survive, but the latter one does not need nutrition, rather deposition from cell organelles. 

  1. Texture

Thickness of plasma membrane or cell membrane remains unchanged throughout its life. In case of a cell wall, it grows with time. 

  1. Functions

Significant functions of plasma membrane include 

  • protection of protoplasm, 

  • assist in communicating between cells, and 

  • Keep track of molecular movements.

Cell wall provides shape to a cell, takes part in morphology, maintains osmotic environment of a cell. It protects the inner organelles from outside forces as well. 

  1. Permeability

Plasma membrane is semi-permeable, and cell wall is entirely permeable. 

Apart from these, the most fundamental difference between plasma membrane and cell wall is that the former one is present in the inner lining of all cells while the latter one protects the membrane (specific cells).  

MCQ: which organelle participates in cell wall synthesis?

  1. Chloroplast

  2. Mitochondria

  3. Lysosome

  4. Golgi apparatus

Ans. 4. 

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FAQ (Frequently Asked Questions)

1. Is cell membrane and plasma membrane the same?

No, they are not the same thing. While cell membrane covers the entire components of a cell, plasma membrane covers only the cell’s organelles. 

2. How is a cell wall different from cell membrane?

Cell membrane is present in all cells while cell wall remains only in bacteria, plants, algae and fungi. Also, cell membrane contains proteins and lipids, whereas cell wall consists of cellulose. Finally, the former one is living, and the latter one is non-living.

3. Where is plasma membrane found?

Plasma membrane is found in all cells. It protects the inner components of the cell from outside environment.