Membranes have many different functions within a typical cell, such as keeping unwanted viruses out, but probably the most valuable is the partitioning of the cell into functional and segregated compartments. Because of the incredible number and often conflicting occurring in a cell at any one time, the cell must retain order via structural organization or risk chemical chaos.
Chaos theory is the field of study in mathematics that studies the behavior of that are highly sensitive to initial conditions—a response popularly referred to as the .
Structure of Cell Membrane
The internal to prevent interference. The structure also separates life from the non-life on its exterior.
In so doing, an intact and healthy membrane is selectively permeable because it allows substances needed for cell prosperity to enter and attempts to prohibit the penetration of unwanted and unfriendly substances. Unfortunately, the system is not always fool-proof. Sometimes unwanted substances pass through the membrane and may cause trouble within the cell.
- The Cell – Structure, and Functions (Synopsis Points)
- Active transport: Cell Membrane Mechanism
- Electrical properties of a membrane
Interestingly, when a phospholipid is placed in water, it spontaneously folds upon itself to create a double layer or bilayer. This is also the foundation for the widely upheld fluid mosaic model of membrane structure.
The has a water-soluble, polar “head” and two fat-soluble, nonpolar “tails.” The hydrophobic tails always try to avoid water and face the inside of the bilayer, whereas the hydrophilic head faces the exterior and the interior.
Within the phospholipid bilayer are many different types of embedded proteins and cholesterol molecules whose presence spawned the term mosaic. From scanning electron microscope images, it was observed that the embedded molecules can move sideways throughout the membrane, meaning the membrane is not solid, but more like a fluid.
The membranes also have glycoproteins attached to their surface, which aid in their location and identification of food, water, waste, and other membrane traffic. The structure of the cell membrane has a particular glycoprotein structure based on its need to attract or repel membrane traffic. Refer to the illustration Typical membrane, and note the arrangement of the phospholipid molecules.
The proteins embedded in the cell membrane serve many of the membrane functions, such as holding the membrane in a regular, identifiable structure for easy bonding. They also have a specific and unique shape that allows them to function as receptors and receptor sites for attachment to the appropriate raw materials needed for cellular functions.
In some cases, the receptor protein is also a signal transducer that begins a series of enzyme-catalyzed reactions to stimulate a particular reaction or function within a cell. Finally, the transport proteins also called carrier proteins, help substances move across membranes, as described in the next section.