Factors+affecting+material+transport


 * By Rachael **
 * Factors Affecting Material Transport**

There are many factors which can affect material transport in and out of the cell membrane and the cell. There are some main factors which are about to be explained. As we already know the plasma membrane is made up of proteins and lipids. The phospholipid bilayer is made up of ‘heads’ and ‘tails’. The heads are known as hydrophilic heads. This means they are ‘water-loving’ and are in contact with the watery environments where as the tails are hydrophobic. This means they are ‘water- repelling’ and face into each other in the centre of the bilayer. Hydrophobic molecules can travel quickly through the plasma membrane and Hydrophilic molecules take much longer to pass through the plasma membrane.

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 * Examples of Substances Which Can Easily Pass Quickly Through the Membrane**

Some examples of substances which can easily pass through the membrane with almost no movement are Hydrophobic molecules. These are molecules such as oxygen, carbon dioxide as well as other small, uncharged particles. Generally, large molecules are unable to pass through the membrane. However, molecules such as hormones can pass through the cell easily. Hydrophilic molecules usually take a longer time to pass through the plasma membrane but water is an exception as it can pass through quite quickly.This is because they are very similar to the Phospholipids which make up the plasma membrane. They pass using a method called Phagocytosis. This is where particles which are too big are 'engulfed' by the plasma membrane and this then forms vesicles. Once formed these vesicles are moved into the cytoplasm.

Click on the link below and it will take you to an interactive website which shows different substances moving in and out of the plasma membrane: []

Selective Permeability means that the plasma membrane has some control over what can and what can't cross over it. This means that only certain molecules can enter and or leave the cell. Watch the video below which explains Selective Permeability media type="youtube" key="hIlq3nXcawY" height="315" width="560"
 * Selective Permeability**

**Examples of Selective Permeability**

Some examples of selective permeability are water, oxygen and carbon dioxide. They are able to travel through the plasma membrane easily and don't have to go through protein channels or go through the process of phagocytosis.