Every living organism and the tissues of the body are composed of cells, the smallest units that are capable of living on their own. Any cell, whether we are talking about plant or animal cells, consists of three main parts: the cell membrane, the cytoplasm, and the nucleus. Obviously, each of these elements has unique roles that are absolutely crucial for the cells to function properly.
The cytoplasm of a cell is surrounded by a thin membrane, called the cell membrane or the plasma membrane. Along with protecting the interior of the cell, this membrane has several other functions, making it pretty much essential. To describe the purpose and uses of the membrane, here are ten reasons why cell membrane is important.
#1. A Cell Membrane Is a Thin Membrane that Surrounds the Cytoplasm of a Cell
A cell membrane, aso known as the plasma membrane, is a thin membrane that encloses the interior of a cell. Along with protecting the inside of the cell, the cell membrane also creates boundaries between the cell and its surrounding environment. While the cell membrane is the outermost membrane of the cell in animals, it is covered by the cell wall in plants, algae, fungi, and bacteria.
#2. A Cell Membrane Is Semi-Permeable Lipid Bilayer
The cell membrane is a lipid bilayer characterized by semi-permeability. The membrane is made up of two layers of lipids (phospholipids) and cholesterols distributed between the layers. Due to the structure and chemical properties of the lipid bilayer, the cell membrane is capable of maintaining membrane fluidity at different temperatures. The lipid bilayer makes the cell membrane flexible and semi-permeable, allowing the cells to not only change their shape but also control the uptake and release of various substances.
#3. A Cell Membrane Is Composed of Phospholipids, Cholesterol, Proteins, and Carbohydrates
Primarily, cell membranes are composed of lipids and proteins. Typically, these are fatty-acid-based lipids, including phospholipids and sterols (oftentimes cholesterol). In terms of proteins, the cell membrane consists of integral and peripheral proteins. While integral membrane proteins are embedded into the lipid bilayer, peripheral membrnae proteins are found on both inner and outer surfaces of the cell membrane. In addition, carbohydrates are often located on the outside surface of the cell while being bount to proteins or lipids, forming glycoproteins and glycolipids, respectively.
#4. A Cell Membrane Is Flexible, Allowing Cells to Change Their Shape
The chemical composition of the cell membrane makes the lipid bilayer exceptionally flexible. Undoubtedly, this is of huge importance for the cells to grow, divide, or even change their shape as needed. While the shape of a cell determines its functions, many cells are capable of changing their shape, especially during the generation of organs or when tissues undergo various transformations. The flexibility and softness of the cell membrane can be explained by the presence of long hydrocarbon chains of the fatty acids in phospholipid molecules.
#5. A Cell Membrane Provides Structural Integrity for the Cell
In order for the cells to function properly, it is crucial for them to maintain the integrity. This is when a cell membrane comes into play. It not only encloses the interior of the cell but also provides structural integrity. As the membrane integrity is essential for the cells to survive, its defects can cause various pathological symptoms and disorders. Without the lipid bilayer of the cell membrane, it would be impossible to maintain the structural integrity of the cells.
#6. A Cell Membrane Protects the Interior of the Cell
Protecting the cell and its interior from the surroundings is the primary function of the cell membrane. As the cell membrane consists of a thin semi-permeable phospholipid bilayer, it selectively permits ions and molecules into and out of the cell. The regulation of the movement of substances in and out of the cell is yet another factor protecting the interior of the cell.
#7. A Cell Membrane Regulates the Transport of Materials Into and Out of the Cell
There are four ways by which substances enter or exit the cells. These are diffusion, osmosis, active transport, and passive transport. In all four cases, substances pass through the cell membrane surrounding the cytoplasm of the cell. As the cell membrane is semi-permeable, it allows certain substances to pass through the membrane while blocking others. In this way, the cell membrane prevents toxic materials from entering and useful materials from leavin the cells.
#8. A Cell Membrane Helps Cells Interact With Each Other
Believe it or not, cells communicate with each other and this can be done by sending and receiving signals. While cells often receive signals from the environment, they may also receive signals from other cells. As plasma membranes have membrane proteins bound to them, they can send and receive signals when needed. Without the cell membrane, cells would not be able to transfer information to each other.
#9. A Cell Membrane Is Involved in Juxtacrine Signaling
As a matter of fact, cells use different types of signals to communicate. The major signaling mechanisms include autocrine, endocrine, paracrine, and juxtacrine mechanisms. While all four signaling pathways are crucial, juxtacrine signaling is the one linked with the cell membrane. In juxtacrine signaling, neighboring cells that physically contact each other send and receive signals through signaling molecules that are bound to the plasma membrane. Without the cell membrane, cells would not have the ability to distinguish different types of neighboring cells from each other through cell-cell recognition.
#10. Without Cell Membranes, Living Organisms Would Not Even Exist
As living organisms have millions if not trillions of cells, there is no doubt that they are of huge importance. And if cells are crucial, so are the cell membranes. In fact, humans possess 30-40 trillion cells, each being enclosed by a cell membrane. Clearly, it would be impossible for different living organisms to exist without the plasma membrane.
