Structure and function of membrane systems in Eukaryotic cells.

Authors Avatar

Structure and Function of Membrane Systems in Eukaryotic Cells

Fatimah Jilani

There are two types of basic cells, one of which is the Eukaryotic cell. The eukaryotic cell has a true (‘eu’) nucleus (‘karyo’). The eukaryotic cell contains the following features:

  • A true nucleus
  • True organelles which are membrane bound
  • And the well known plasmamembrane.

In this essay, I shall explore the structure and function of cell membranes in eukaryotic cells.

There is unknown to biologists any cell that does not have a membrane surrounding it and in eukaryotic cells most of the cell components are surrounded by a membrane too. It is an extremely thin cell structure and is only visible through the electron microscope measuring only up to 10nm thick. However small it is, the membrane makes up and plays an important function in living organisms. Both the cell surface membrane and the membranes surrounding certain organelles have the same basic structure.

The cell membrane is made up from a phospholipid bilayer. The phosphate heads are polar molecules and so are water-soluble. The lipid tails are non-polar and therefore are not water-soluble. This means that the phospholipids are arranged with the heads in contact with the cytoplasm or extra-cellular fluid, both of which are watery environments. The tails are protected from this, by being as far from the cytoplasm and extra-cellular fluid as possible. In between the phospholipid, molecules there are cholesterol molecules. Cell surface membranes of animal cells may contain almost equal number of cholesterol molecules whereas plant cell surface membranes contain molecules, which are similar to cholesterol. The role of the cholesterol molecules is to keep the membrane constantly fluid. So, the cholesterol makes the membrane more fluid at low temperatures and not so fluid at high temperatures.

Join now!

Alongside that, there are protein molecules in the membrane and these protein molecules play the role of transporters, allowing transport of substances to pass through the membrane from either side. These proteins mostly tend to have chains of carbohydrates attached and these are known as glycoproteins. These glycoproteins are always positioned on the outer surface of the membrane. These glycoproteins help to stabilise the structure of the membrane as well as their involvement in cell recognition.

The cell membrane is referred to normally as ‘the fluid mosaic model.’ The reason for this name being kept is that the molecules in ...

This is a preview of the whole essay