Plasma membrane: what is, functions and structure

The plasma membrane is a Cell component that delimits it outsidebeing one of the outermost and delimiting structures. It is also known as Cell membrane or cytoplasmic membrane. The characteristics of the plasma membrane are:

• Selective permeability: The average plasma membrane which can enter and leave the cell, as well as prevents the passage or output of compounds that should not be transported thanks to selective proteins. For example, nutrients enter, and metabolic waste comes out. The pH and ionic balance are also regulated. These processes are regulated by osmosis.
• Flexibility: This membrane has fluency that allows you to give the cell, while containing all the provisions inside the interior.

In this other article you can learn more about cytoplasm: what is, function and structure.

The functions of the plasma membrane vary according to the composition and type of cell, but all plasma membranes meet the following activities:

• Barrier function: It is a permeable barrier that divides the aqueous intracellular environment with the dispersed organelles, with the outside of the cell. This helps protect inside the cell.
• Keep the electrochemical gradient: This is produced by the difference of ions inside and outside the cell, whose load differences is what produces the electric and chemical gradient. An example of this gradient is the Sodium-Potasio pump, which produces energy.
• Transport of small molecules: The plasma membrane allows the passage of certain molecules, helping to meet different processes. This transport can be liabilities, where molecules move in favor of the electrochemical gradient without requiring energy, or actively where transport is against electrochemical gradient
• Communication: At the same time that it works as a barrier, the membrane selectivity serves so that the cells can communicate with each other, leaving the passage of metabolites that are needed for different processes. This communication is made both between cells, as between a cell and the environment, with the help of signaling that the cell interprets through receptors and molecules. In addition, the signals can be of an electrical type, to be detected with neurotransmitters or with ionic channels.
• Cellular motility: The plasma membrane is better understood with the fluid mosaic model, where the layer is inside a fluid, giving mobility to the cell along with other characteristics that perform particular functions of the membrane.
• Medium: The membrane helps reinforce tissues, giving them support, shape and helping to unite cells. This is achieved thanks to the fact that the plasma membrane joins the cytoskeleton by certain intracellular proteins.
• Cellular signaling: Eukaryotic cells have a system for signal transduction, in which signals are activated from substances external to the cell so that a certain receiver is activated, and with it a particular function is carried out.

Just as the function varies according to the membrane, the structure also varies, but all plasma membranes have the following basic components:

• Lipids: The membrane is a lipid bilayer, which means that there is a hydrophilic head that attracts water, and a hydrophobic tail that repels water. This simple principle that lipids repel water, is what allows cells to be delimited by said cell membrane.
• Carbohydrates: These are carbohydrates, and adhere to lipids and proteins.
• Proteins: These proteins can be intrinsic, which are inserted in lipid bilayer, or can be extrinsic that are peripheral proteins located at the ends of lipids or proteins, but are not properly inside the membrane. In addition, proteins are divided into glycoproteins, which are those that are nest sugar to a protein, or lipoproteins, which are the union of a lipid with a protein.

In addition to these basic structures, plasma membranes can have additional variations or structures according to the type of protein. Some examples are:

• High cholesterol level: Animal cells have a lot of cholesterol to give stability and firmness to cells, since they lack cell wall as plant cells have it.
• Anchoring of Motile Structures: Some prokaryotic cells have structures that serve them to move, such as flagella. These are detached from the plasma membrane.
• Glucocaliz: It is in some plasma membranes of bacterial cells, and in mucous cells in animals. This glucocaliz helps to secrete a mucilage layer, which serves as protection.
• Exoenzymes: These are particularly in prokaryotic cells, and are the result of catabolism, forming enzymes that can be used outside the cell.

Now you have more knowledge about what is the plasma, cellular or cytoplasmic membrane, its functions and its structure. Therefore, you may be interested in learning about mesosomas: definition, function and composition.

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