what is pulse - field gel electrophoresis?
81840
Think of a gel as a web of fibers, either polyacylamide or acrose.  This web creates a maze for the molecules to run through with the smallest molecules advancing faster than the larger molecules.\n\nDNA, in particular, creates a problem.  The molecules are very long and fiber-like.  They have a tendency to get hung up on the fibers of the gel.  Pulse field electrophoresis provides a solution.\n\nIn pulse field electophoresis, the voltage difference across the gel is reversed repeatedly to prevent the problem of the molecules getting stuck on the fibers of the gel.  Initially, the positive charge is placed at the bottom of the gel.  As the DNA moves to the positive end, some of the molecules will get hung up.  So, at some point in time, the field is reversed so the positive charge is at the top of the gel.  The DNA molecules then move to the top of the gel.  Any hung up molecules are then freed.  Then the field is reversed again, so the molecules can continue their journey to the bottom of the gel.  The process is repeated several time throughout a gel run.
569604
It's a process where DNA is moved and separated by electrical currents bands are formed on a gel called agarose.  It shows similarities and differences between relations and non relatives.  The gel created is unique to you and therefore is how DNA testing can tell if the DNA supplied came from a certain source
171613
Electrophoresis, x-ray diffraction (x-ray crystallography), chromatography (usually use for plant cell), centrifugation, microscope, and by using fluorescence technology
93644
I use a 1 KB DNA ladder for electrophoresis and it comes with a paper to actually tell you which band represents which size fragment. Maybe you could look on the tech company's website. If you do not need to know the actual fragment size of each band, maybe you could just compare to make sure the band you need is there in the first place.
899184
Gel electrophoresis is much more cheap, fast, simple to do (and troubleshoot) and requires much less sample to do. Also it is much more flexible since it is extremely easy to prepare a more or less concentrated gel (if you are not satisfied with the first run) and achieve better resolution (and more accurate MW calculation). You can also do this with gel chromatography but it is a real pain to change the stationary phase (the gel) and pass standards through the column to get a new standard curve.\n\nAlso gel chromatography (with molecular shieves) you would use mainly as a preparative method, that is not just to separate proteins according to their size but also to isolate them.\n\nThere might be even more differences, but I think that the ones I already mentioned are the most important/basic ones.
111490
Ahh...thats easy...After putting the DNA in the holes, and turning on the electric field, DNAs move to the (+) pole because they have a (-) charge....Small DNAs move faster and they separate so the result is seen on the gel...
8687
mRNA  \nCapped messenger RNA is produced directly from your plasmid that contains a T7 or SP6 promoter. It is purified by our proprietary PUREmessenger™ technology. PUREmessenger™ is a chromatography that not only eliminates traces of DNA and proteins but also allows the selective recovery of the mRNA of the correct size. Shorter abortive transcripts as well as longer contaminating mRNA that are produced during in vitro transcription are eliminated. Capped mRNA will be purified by PUREmessenger™, quantified, re-suspended at 1mg/ml (except if otherwise specified) and aliquoted at 50 µl/aliquot (except if otherwise specified) in sterile conditions. It will be sent to you on cooling blocks together with its documentation: formaldehyde/agarose gel documentation picture. The capped mRNA that is sent to you ready-to-use (dissolved in water or the buffer of your choice) is 100% of your mRNA molecule of interest.\n\nCapped mRNA is produced in clean room facilities for research or clinical applications.\nYour benefit\nHighly purified, efficiently capped mRNA that has a superior efficacy compared to standard mRNA produced with in vitro transcription kits and simply purified by precipitation thus contaminated with alternative transcripts and traces of proteins and DNA fragments. The high quality of mRNA is reproduced from batch to batch. This guarantees the consistency of your results. Capped mRNA can be produced for research or for clinical utilisation: "documented" to be used as Active Pharmaceutical Ingredient or GMP-certified.
751016
Gel filtration is a type of size exclusion chromatography where your packing material is made of silica or a polymer containing a network of uniform pores.  Larger molecules cannot get into the pores so elute more quickly, smaller molecules the opposite.\n\nTo measure molecular weight of an unknown protein you would first need to produce a calibration plot by running through a series of standard proteins of known molecular weight and measuring the elution time for each.  You would then produce a calibration plot of log molecular weight versus elution time (note the log here).  Then finally you would run your unknown protein through, measure it's elution time and then use your graph to get its log molecular weight and hence its molecular weight!!
1023558
I think it is a mechanical technique.  The powder simply sticks in the oils from the skin left behind on the surface. I am not up on modern techniques, but perhaps some chemical reaction between the powder and some treated paper allows investigators to make copies of the prints.\n\nElectrophoresis is a technique where an applied electric field causes charged molecules to move through a medium; usually a gel these days but paper used to be used.  Larger molecules tend to move more slowly, and more highly charged molecules will move more quickly, so you can separate compounds.  I don't see how this might be used in fingerprinting.
414422
PCR involves\na) marking a region of DNA with borders (also called primers), say A and B, and then\nb) amplifying the DNA flanked by these primers. \n\nFor DNA finger printing, the A and B are chosen such that the, region between them varies in length across individuals. This is because certain elements (i.e., stretches of nucleotides) present between the A and B vary in their number. So, when PCR is performed, the product length varies depending on the template DNA taken from different individuals. \n\nBy the electrophoresis technique, the PCR products of different length can be visualized and one can detect the differences between the individuals. Thus, the VNTR (variable number of tandem repeats) among individuals is the basis of DNA finger printing by PCR.
331206
It's basically like a southern/northern/western except that you don't do electrophoresis.  What you do is drop your sample onto a membrane, then probe the membrane with whatever (antibodies for western, radioactive probe for RNA/DNA).
823770
liquid chromatography  separates by charge at a given pH\ngel chromatography  separates by size\n\nthen there is electrophoresis\n\nNow would be a good time to point out I failed one biochemistry exam 4 times\n\ngood luck.
597037
I dont know if this is it, but go here at: http://www.ks.uiuc.edu/Research/pro_DNA/ster_horm_rec/
6224
Sequence profiling tools in bioinformatics refer to all those software tools (web-based/downloadable) that provide a brief overview on all related information about an input sequence.\n\nThe advent of post-genomics era has given rise to a range of web based tools and software to handle the deluge of biological information. A simple web-search returns any number of such services and software tools ranging from the popular public domains e.g. NCBI, ExPASy, Ensembl, PDB etc to private research group sites e.g. eF-site, Dipole moment server, SuperPose, REBASE. However, most of these remain obscure/under-explored to a bench-top molecular biologist who most often would like to quickly know which record in the BLAST report is useful for further analysis (given that the first few hits are already known) OR like to have a guess at what would a newly found ORF look like after translation.
516829
Preparative HPLC should do the trick.  Try a search at these to see if an exact procedure might be on the web.\n\n\nhttp://www.scienceresearch.com/search/\n\nhttp://www.scirus.com/srsapp/
671418
PCR is a technique in which a specific stretch of DNA is amplfied greatly (a billion-fold or more).  Briefly, two small stretches of cDNA are designes that will bind to a stretch of DNA-almost like bookends. Then a Taq polymerase is added, which produces a complete cDNA starting from each primer.  Then the solution is heated, and the strands melt apart, then it's cooled, new primers bind (now there are twice as many stretches of that DNA) and the reaction is run again- Each time the reaction is performed, it doubles the amount of that specific DNA strand.  "Taq" polymerase is special in that it comes from a bacteria that lives in extremely high temperatures, so the melting phase of the reaction doesn't denature it.
648999
SDS-PAGE is a type of electrophoresis used to separate proteins based on their relative sizes. The polyacrylamide gel is formed when free radicals produced by ammonium persulfate cause the polymerization of acrylamide and bis. A chemical called TEMED is added to stablize the free radicals. Tris is used as a buffer. Prior to electrophoresis you sample is treated with a buffer containing Sodium dodecylsulfate (SDS) and beta-mercaptoethanol (b-ME) and boiled. The boiling denatures the proteins by breaking all the hydrogen bonds that form the alpha-helix and the beta-pleated sheet structures. The SDS is a detergent that wraps around all the proteins in your sample and gives all the proteins a negative charge. The b-ME breaks the disulfide brigdes within the protein strand. The proteins will now be able to move through the gel as a function of their size only because they will all have the same relative charge.