ACTIVE AND PASSIVE TRANSPORT


Website:
http://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/passive.html
http://biology.about.com/library/weekly/aa053101a.htm
http://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/osmosis.html
http://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/diffusion_f.html
http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/diffus.html
http://staff.jccc.net/PDECELL/cells/activet.html
http://www.zerobio.com/central/na_k.htm
http://onlinebiotext.wikispaces.com/Active+vs+Passive+Transport
http://horts-bio-class4.wikispaces.com/message/view/horts-bio-class5/1587093
http://nwbiology.wikispaces.com/Amniocentesis
http://bthsgatewaybio.wikispaces.com/Chorionic+Villus+Sampling+

Active transport uses energy to send substances against the concentration gradient. This means that the substances travel from a region of low concentration to a region of high concentration. Active transport is used to generate charge gradient. In addition to this, active transport is used to concentrate ions, materials, and nutrients inside the cell that are in low concentration outside of the cell. Lastly, active transport is used to keep unwanted ions or other molecules out of the cell that are able to diffuse through the cell membrane. One example of an active transport is a sodium-potassium pump.




Passive transport is the movement of molecules or ion down the concentration gradient. Unlike active transport, passive transport doesn't require energy. One example of a passive transport is diffusion. Diffusion moves material from an area of high concentration to an area of low concentration. Another example of a passive transport is facilitated diffusion. Facilitated diffusion is the movement of molecules through the cell membrane using special transport protein that are embedded within the cellular membrane. Osmosis is another exmaple of a passive transport. Osmosis is the diffusion of water molecules across a partially permeable membrane from a region of high concentration to a region of low concentration.

Sodium-Potassium pump
external image pump.gif
http://www.nurseminerva.co.uk/images/pump.gif
external image GB1-os19.jpg
http://faculty.southwest.tn.edu/rburkett/GB1-os19.jpg