Science

Differences between Membrane and Cell Wall

The plasma membrane and the cell wall are two important parts that make up the cell, where a cell is the smallest structural and functional microscopic unit that living beings possess.

As is known, there are two types of cells, prokaryotes and eukaryotes, prokaryotic cells are self-sufficient cells like bacteria and eukaryotic cells are the cells of all multicellular beings. Both animals and plants have eukaryotic cells although they have different structures.

That is why both the plasma membrane and the cell wall are elements of great importance for the fulfillment of the structural functions of the various types of cells, so it is of our particular interest to point out their characteristics and differences in this article. .

plasma membrane

The plasma membrane or cell membrane is a laminar structure (in the form of a sheet) formed by phospholipids and proteins that surround the cell defining its limits. Its main characteristic is selective permeability, a capacity that allows it to receive signals to select the molecules that must enter and leave the cell.

Among other basic functions of the plasmatic or cellular membrane we can find:

  • Helps maintain the intracellular environment differentiated from the environment.
  • It allows the cell to divide, into sections, the different organelles (functional unit of a cell) and thus protect the chemical reactions that occur in each one.
  • It creates a selectively permeable barrier where only the strictly necessary substances enter or leave.
  • It transports substances that can be used by the cell for its metabolism from one place in the membrane to another.
  • It perceives and reacts to stimuli caused by external substances and regulates the interactions that occur between cells.

It is worth noting that the plasma membrane or cell membrane is present in all kinds of cells, including plant and animal cells, and its main function is not only to regulate what enters and leaves the cell, but also to shape it and ensures that parts of it are contained.

Cellular wall

The cell wall is a layer that surrounds the entire cell and can be rigid or flexible depending on the type. It is made up of cellulose in plant cells while in bacteria, fungi and algae it is made up of substances such as peptidoglycan, chitin, glycoproteins, polysaccharides or pseudopeptidoglycan.

The cell wall is not found in animal cells or protozoa, it is only present in plant cells, as well as in bacteria, fungi, algae and some archaea. In the same way, it is an integral part of these cells whose main purpose is to provide protection and shape to the cell, giving it rigidity and allowing it to maintain its shape even under pressure and especially when there is a lack or excess of water in it.

The cell wall is responsible for what enters and leaves the cell, it controls all transfer of substances between the inside and outside of the cell, it has some holes called plasmodesmata that are responsible for allowing nutrients to enter the cell, so that, allows the residues to come out and the ions to pass through it.

Once the concepts that concern us have been defined, the following differences between membrane and cell wall are pointed out:

  • The plasma membrane or cell membrane is present in all types of cells (animal, plant, algae, fungi and bacteria) but the cell wall is only present in plant cells, bacteria, fungi, algae and archaea.
  • The cell membrane is a functional part of all cells and the cell wall is a functional part of prokaryotic cells.

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