What is a plasma membrane?
Plasma membrane, also known as the cellular membrane, is an essential part of the cell that closes the internal components of the cell and allows only certain parts of the external environment to enter. This membrane is one of the few parts that have common prokaryotic, eukaryotic, plant and animal cells. The plasma membrane is much more than a simple barrier; It controls what moves to and out of the cell, and controls many interactions that occur between the cell and its environment. The membrane consists of many different molecules and proteins that move somewhat smoothly, leading to the description of the plasma membrane "fluid mosaic".
The most abundant molecules in the plasma membrane are phospholipids that are made of hydrophobic, "tail" and hydrophilic head, "water". Two layers of phospholipids arranged with hydrophobic tails on the inside form a phospholipid double -layer that provides the primary structure of membrane. These double -layers prevent large substances or especially polar substances passively difunds over the cell membrane.
Many proteins that allow the transport of large or polar substances over the membrane are built into the phospholipid double -layer. Some allow passive diffusion of substances in and out of the cell; This does not require any energy. Others actively carry substances from one side of the membrane to the other. This process, generally referred to as active transport, requires small energy expenditure. Not all substances can always move and out of the plasma membrane, so it is said to be "selectively permeable".
Plasma membrane also plays an important role in positioning, anchoring and shaping the cell when connecting adjacent cells. Extracellular structural components that form the extracellular matrix, Conekt into the cell on the cell membrane. Cell walls that provide rigidity of plant cells and some bacteria and other small organisms also tend to join plasmAtic membrane of the cell.
cell communication is another important function of the plasma membrane. Proteins and protein receptors built into the membrane can send and receive chemical signals. Some of these signals cheat cells to a certain form of effect, such as absorption or exclusion of specific substances. Other chemical signals serve as identification mechanisms and allow the cells to be recognized. This is particularly important in the immune system, so the immune response of the body focuses only on harmful cells and does not damage the normal cells of the body.