What are the properties of a plasma membrane in an animal cell?
vincent d asked:
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.
BEVERLEY
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.
BEVERLEY
January 6th, 2009 at 4:33 pm
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.
January 8th, 2009 at 5:16 pm
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.