What are the properties of a plasma membrane in an animal cell?

Question

We all know that the plasma membrane is a highly selective membrane of an animal cell that limits the passage of water and water soluble components of substances that goes in and out of the cell. It also separates the cell from the outside environment. These are some functions of the plasma membrane, but what are its properties? I will be waiting for you reply, thank you.

Answer 1

To perform the function of the organelle, the membrane is specialized in that it contains specific proteins and lipid components that enable it to perform its unique roles for that cell or organelle. In the cell membrane, phospholipid molecules create a spherical three dimensional lipid bilayer shell around the cell. A phospholipid molecule is composed of a head and two tails. The circle, or head, is the negatively charged polar phosphate group and the two tails are the two highly hydrophobic non-polar fatty acid chains of the phospholipid. The plasma membrane consists of 1/3 cholesterol and 2/3 phospholipids (65-80%) and sphingolipids (20-35%). The outer leaflet contains 5% glycolipids.

Answer 2

The plasma membrane's properties actually determine its functions.
The plasma membrane is a complex monolayer film consisting largely of amphoteric polar phophoplipid molecules arranged in a lowest-energy configuration where the water-loving heads are exposed to water inside and outside the cell, and the water-hating carbon-chain tails associate with one another. This creates a "bi-layer" that is hydrophilic on the surfaces and hydrophilic inside the thickness of the film. (This is exactly the opposite of a soap bubble, BTW.) The bilayer is associated with proteins, some of which cross the bilayer and facilitate the transfer of materials such as ions and simple organic compounds across the membrane. Other membrane-associated proteins stabilize the membrane or may be involved in changes in membrane shape associated with vesicular uptake of larger molecules. While the PM may be viewed as the thing that separates the inside of the cell from its outside environment, it is also the dynamic interface that allows the cell to communicate with that environment for homeostasis and physiological response. This communication is largely accomplished by proteins and protein complexs associated with (and crossing) the bilayer that act as receptors for molecules in the extracellular water. Binding to these receptors leads directly to biochemical events inside the cell that influence the metabolism and actions of the cell.

Membrane biology is fascinating and complex. Many PhD candidates in physiology, biochemistry, pharmacology, and anatomy do their dissertation work on problems in this area. (I did.)

To answer your question in a nutshell, the plasma membrane's properties are:
1. Fluid phospholipid (with other lipids) bilayer
2. Semipermeable
3. Transport and structural dynamics dependent upon associated proteins.

Answer 3

It's known as a Phospholipid Bi-layer. There are two layers of Phospholipids with hydrophillic heads facing outwards and hydrophobic tails facing inwards. This means that water soluble molecules can't get through the interior of the bi-layer. It is known as a fluid mosaic model as the phospholipids are free to move. The phospholipids are interspersed with: Cholesterol - This provides stability Glycoproteins and glycolipids - Glycoproteins are involved in cell recognition whilst the function of glycolipids isn't known fully. Membrane channel proteins - Forms a channel through the bi-layer to allow large or polar molecules to pass through the bi-layer via facilitated diffusion. Membrane carrier proteins - Uses Adenosine Triphosphate to change the shape of the protein to transport molecules from one side of the bi-layer to the other AGAINST a concentration gradient via active transport.