Cell Membrane and Plasma Membrane

Cell Membrane

The cell membrane is a narrow layer that envelops all functioning cell and separates it from its surroundings. The cell’s components, which are generally big, water-soluble, extremely energised molecules like nucleic acids, proteins, carbohydrates, and materials engaged in cellular metabolism, are encompassed by the cell membrane. Acids, ions and alkalis that are harmful to cells can be found beyond the cell in the ambient water-based medium, along with nourishment that the cell needs to survive and flourish.

Lipids made of fatty-acid and proteins make up the majority of cell membranes. Phospholipids and sterols (usually cholesterol) are the two main forms of membrane lipids. Both varieties have an area that is drawn to and dissolves in water, which is a distinctive trait of lipids—they dissolve quickly in organic solvents. The significance of lipids as structural elements of cellular membranes is fundamentally dependent on their “amphiphilic” feature (carrying a double tendency; i.e., including both water-soluble and lipid-soluble parts). In principle, membranes that are actively engaged in metabolism have a higher protein content.

Plasma Membrane

The different organelles or the components of a cell are surrounded by the plasma membrane. The cell membrane is a sort of plasma membrane that surrounds the cell and protects it from the environment. Plasma membranes are seen enclosing a cell’s cytoplasm and components, as well as particular organelles like mitochondria and chloroplasts.

This implies that plasma membrane serves a variety of purposes according to their location. The membrane’s shape and composition may vary based on what it envelopes, if it is the total cell or a single organelle within it. Irrespective of whatever component they surround, plasma membranes typically deliver some level of protection, and several often play a part in phosphorylation processes.

Plasma membranes surrounding the organelle show selective permeability, cautiously looking out for what compounds enter into and exit the organelle, but the molecules that the organelle requires will vary. Because the organelles have various roles, the chemicals that must enter and exit a mitochondria differ from those that must enter and leave a chloroplast.

For example, pyruvate must penetrate mitochondria to enable aerobic cellular respiration to take place, whereas carbon dioxide must permeate chloroplasts for photosynthesis to take place.

The working of the membranes:

Cell Membrane

The cell membrane’s chemical nature helps it to be extremely elastic, making it an excellent border for quickly forming and multiplying cells. However, the membrane is a powerful wall that enables certain soluble materials, or solutes, to flow through while preventing others. Small molecules and lipid-soluble substances can pass through the membrane, but still, the bilayer of the lipid efficiently resists the numerous big, water-soluble substances and highly energised ions that the cell needs to keep out or take in to survive.

The cell membrane experiences coordinated motions in order to carry out transmembrane motions of big molecules, during which portion of the surrounding fluid beyond the cell is internalised (endocytosis) or a portion of the cell’s internal fluid is externalised (exocytosis). The merging of the membrane layers is preceded by the re-formation of whole membranes in these events.

Plasma Membrane

The plasma membrane serves as a protective border between the outside and the internal organelles of the cell. It is a partially permeable layer that allows just particular molecules to pass through it into and outside of the cell. Both the exocytosis and the endocytosis processes rely heavily on plasma membranes. It also serves to enhance cell-to-cell interaction and signalling. The plasma membrane is responsible for attaching the cytoskeleton, which gives the cell its form, as well as preserving the cell’s potential.

Difference between Cell Membrane and Plasma Membrane:

The position of the Membranes

The cell membrane is solely located around the cell’s contents, but the plasma membrane is also present around some organelles.

Their Tonicity

The cell membrane is generally engaged in tonicity management; however, this is not true of all plasma membranes.

Defence against intruders

The cell membrane serves to shield the cell from viral and bacterial invasion, but other plasma membranes within the cell do not do this.

Signal Transduction

The cell membrane includes the earliest receptors for signal transduction procedures and so is the primary step in signal transduction when messages from other cells are acquired. The plasma membranes that enclose organelles are not the initial step in signal transduction, although they do play a role.

Cytokinesis in the Membrane

In cell division, phospholipids perform an important function in cytokinesis in the cell membrane. Plasma membranes, which are not cell membranes, are not like this.

Antimicrobials’ targets

Antimicrobial agents can attack the cell membrane of fungi and bacteria. If they are not cell membranes, plasma membranes are not attacked.

Conclusion

The cell membrane is a sort of plasma membrane that wraps all of a cell’s components, including its cytoplasm and organelles. Plant cells feature a cell wall that additionally wraps the cell membrane; therefore, it is not necessarily the uppermost membrane of the cell. Animal cells, on the other hand, lack a cell wall, so cell membranes serve as a boundary between the cell’s interior components and the outside surroundings. Both the cell membrane and the plasma membrane allow molecules to pass through selectively.