Gel+Electrophoresis

= ** Definitions:** =  =Gel Electrophoresi **s** is a technique of analyzing cloned DNA in an indirect way in order to make fast comparisons. The technique is based on macromolecule size, electrical charge, and physical properties. DNA molecules of the same length are found on the same band in this procedure. =

= **Southern Blotting** can compare DNA samples from three individuals. It's invaluable to biologists when looking at noncoding DNA, which is most the the DNA of animals and plant genomes. The DNA has differences in placement of restriction fragments known as restriction fragment length polymorphisms (RFLPs). These locations serve as genetic markers for particular locations in the genome. =

= **Northern Blotting** is the transferring of separate RNA molecules from a gel onto a sheet that is then blocked to binding and immersed in a labeled probe that will hybridize to RNA. =




 * Process of Gel Electrophoresis and Blotting **
 * 1) ** Restriction fragment preparation ** . DNA samples that are tested are prepared from their appropriate sources. A restriction enzyme is then added to the samples of DNA to produce restriction fragments.
 * 2) ** Electrophoresis ** . The restriction fragment mixtures are then separated by electrophoresis. Each of the samples creates a pattern of bands. The bands are not visible unless you stain them.
 * 3) ** Blotting ** . It pulls an alkaline solution upward, which goes through the gel and through a sheet of nitrocellulose paper laid on top of it, transferring the DNA to the paper and denaturing it in the process. The strands of DNA stick to the paper, arranging the bands exactly as on the gel.
 * 4) ** Hybridization with radioactive probe ** . The blotted paper is exposed to a radioactive solution labeled probe. The single-stranded probe DNA is complementary to the DNA sequence that is of interest, and it attaches by base-pairing to the restriction fragments of the complementary sequence.
 * 5) ** Autoradiography ** . A photographic film sheet is laid over the paper. The radioactivity that is in the probe exposes the film to make an image that matches up to the specific DNA bands.

http://www.accessexcellence.org/RC/VL/GG/ecb/ecb_images/10_14_1_Southern_blotting.jpg http://www.everythingbio.com/glos/definition.php?word=Northern+blot http://www.biologyreference.com/images/biol_02_img0140.jpg