METHODS OF TRANSPORT ACROSS A PLASMA MEMBRANE BIOLOGY

The plasma membrane is present in both the eukaryotic and prokaryotic cell and is also known as the biological membrane and. It works as a barrier between the inner and outer surface of a cell hence is also called the cell membrane. In plant cells it is present just beneath the cell wall whereas in animal cells the plasma is present in the outer most layer of the cell. It is vital for materials to be able to move through the plasma membrane in order for the cell cytoplasm to communicate with the external environment. There are number of mechanisms through which this movement occurs. The different types of transport methods are:

Diffusion: There are 2 types of diffusion.

The movement of molecules from a higher concentration area to an area with lower concentration to the point where they are equally distributed is known as simple diffusion. This process is a passive one hence does not require any form of energy from respiration to be carried out. Also the greater the concentration gradient is the more increased rate of diffusion is.

Facilitated diffusion is the process where ions and polar molecules are transported across membranes by channel proteins and carrier proteins. The difference between the two forms of  proteins i.e. channel proteins and carrier proteins is that the former have a fixed shape whereas the latter change shape as they transfer molecules, e.g., when glucose is moved across the membrane.  This form of diffusion i.e. facilitated diffusion also does not need energy from respiration.

Image 1.1

Adela Waters, (2017), Passive Transport across Membrane [ONLINE]. Available at: www.slideplayer.com/slide/10435337/ [Accessed 2 November 2018].

Osmosis: