Dictionary > Selective permeability

Selective permeability

A feature and a function of the plasma membrane that is essential to maintain homeostasis by regulating the passage of some substances while preventing others from entering the cell
Selective permeability refers to the one of the distinctive characteristics of the plasma membrane. The plasma membrane is the membrane that contains the cytoplasm. In the animal cell, it is the outermost covering. In a plant cell, the plasma membrane is found beneath the cell wall. The plasma membrane is capable of being selectively permeable because of its structure. It is composed of a bilayer of phospholipids interspersed with proteins. The phospholipid part of the plasma membrane renders the latter hydrophobic and therefore polar molecules would not be able to easily pass through this layer. The proteins embedded on the plasma membrane act as transporters or channels for certain molecules (e.g. ions). Thus, the composition and structure of the plasma membrane makes the latter semipermeable, i.e. selective to the entry of certain molecules and substances. This means that not all substance would be able to gain entry or exit through the cell. The selective permeability of the plasma membrane helps the latter to carry out an important function of controlling or regulating the passing through of substances between the external environment and the cytoplasm.
See also:

You will also like...

Peppered moth ("Biston betularia") melanic and light form
Examples of Natural Selection

Darwin's Finches are an example of natural selection in action. They are an excellent example of the way species' gene p..

Genetic Mutations
Chromosome Mutations – II

This tutorial is a continuation of the first lesson on chromosomal mutation. Here, find out the chromosomal aberrations ..


This tutorial presents Gregor Mendel's law of dominance. Learn more about this form of inheritance and how it can be pre..

Homeostasis by water regulation
Homeostasis of Organism Water Regulation

Osmoregulation is the regulation of water concentrations in the bloodstream, effectively controlling the amount of water..

Fossil trilobite imprint in the sediment

There are more species of insects than any other species combined. This surely illustrates that insects have the selecti..

Plant Water Regulation
Plant Water Regulation

Plants need to regulate water in order to stay upright and structurally stable. Find out the different evolutionary adap..