CSEC - Movement of substances

Movement of Substances

Here are the links to see an animation of each movement process discussed in class.

Things to know before we begin

1. Substances move throughout, in and out of cells by passive and active media. 
2. A concentration gradient is required to direct the movement
3. Substances moved are varied and they include small, large, charged and neutral particles

Lets put all this together with a concept map                                                                                    

Now for the details:

• A concentration gradient exists when molecules are not evenly distributed. that means you will have a region having more molecules than another. This difference in the amount of molecules is the concentration gradient.                                                    

• Movement along a concentration gradient - from an area of high concentration to an area of low concentration.

• Movement against a concentration gradient - from an area of low concentration to an area of high concentration.

• Passive processes do not require energy. These include:
• Diffusion - 
• Osmosis

• Active processes require ATP energy.
• active transport 

1. Diffusion - movement of uncharged molecules along a concentration gradient, until evenly distributed. eg. perfume in air, red dye in water, oxygen in cells.                   CLICK HERE to see diffusion                                                                                              
2. Osmosis - movement of water molecules through a selectively permeable membrane, along a concentration gradient, until evenly distributed.                                      CLICK HERE to see osmosis                                                                                            
3. Active Transport - movement of charged particles (ions) against a concentration gradient through carrier proteins (gates) with the help of energy.                             CLICK HERE to see active transport                                                                             
4. Endocytosis - the intake of substances into a cell by the folding of the membrane (invagination) into a vacuole.                                                                             > phagocytosis - intake of solid material into a cell                                             >pinocytosis - intake of liquid material into the cell                                                                                                                               
5. Exocytosis - the release of the contents of a cell vacuole to the outside of the cell by fusion of the vacuole with the cell membrane.                                                         CLICK HERE to see endocytosis & exocytosis