How does an automatic DNA sequencer work? plzzz no copy from internet.?
412034
There are various methods to sequence.\nThe current method is have a primer that can anneal to a segment prior to the region you wish to sequence. You then extend the primer using a polymerase, dNTPs and fluorescent terminating nucleotides.  Once the fluorescent terminating nucleotide is incorporated the sequencing is terminated for that sequence.  You will end up with a collection of DNA fragments of different lengths that are a copy of the DNA you wish to sequnce.  These fragments are run through a gel and separated based on size.  Each terminating fluorescent nucleotide is a different color for A, C, G and T.  Based on which fluorsecent nucleotide is present at position you know the nucleotide that is there due to the color. \nFrom this you get the DNA sequence.\nWasn't that easy!
730267
Mass-spectrometry (MS) is the only technique that gives true quantitative answers with extremely high certainty, but MS of DNA is uncommon and hard to do.  A more typical approach would be to "run a gel" separate the different fragments based on size: you have a porous matrix, you place the mixture of DNA pieces on one end, you apply a voltage.  Since the DNA is charged it migrates on the gel, but the bigger pieces are hindered by the matrix (the gel).  You then run a "standard" side-by-side with your unknown mixture--something with a mixture of a few fragments on known size.  Typically these "standard ladders" which are commercially available come in increments, e.g. 100 bp, 500 bp, 1000 bp, etc.  So you will be able to tell the size is between those fragment lengths (e.g. that a band from your unknown mixture is between 100 and 500 bp) with very high certainty, but you do not know the exact length with any certainty.\n\nAlternatively you can sequence DNA--this is very easy and cheap now-a-days, and has a very high-certainty.  So after doing a gel you can cut out the different bands and have them sequenced individually.  Both steps--the gel and the sequencing--are very routine, cheap, and reliable.
543681
We use Sequenom mass spec genotyping here.\n\nThe mass spec costs a lot, and it's not as cost-effective at really high throughput levels (say, running thousands of assays at a time) as some other systems.  But if you want to change your panel of assays frequently, or you want the ability to easily check lots of samples against a small set of assyas, it's very doable on a Sequenom system.  It would be pretty much impossible, or ludicrously expensive to run, say, 10 assays against 500 samples on an Illumina or an Affy genotyping set-up.
899729
To ensure DNA is passed on correctly  the chromosmes tightly pack the DNA along with Histone proteins which basically protect it. During cell division when the cell  is divinding the proteins detach themselves fromthe DNA to allow for copying to take place. The copying is carried out by variious enzymes which many of which include those which acarry out proof reading  i.e error corrections. more specifically they prevent   wrong sequences from being copied. bear in mind in the human DNA is 3 Billion base paries long. so on average 2-3 nucleotides are mutations in each cell cycle. These generally go unoticed as they are silent mutations. The cell cycle is one of the most important reactions in any species and so naturally it has evolved to be as perfect as possible, hene it has a very high level of controll at every stage. sometimes these fail  hence it leads to things like cancers etc ..
142768
Some of the best DNA sequencing machines out there move at about 600Kb per 8 hour shifts...\n\nIf we compare this to the Human Genome, then we get the following basic equation:\n\nThere is about 3 billion base pairs in a single genome, thus equaling 3,000,000 kb to be sequenced.\n\nFor this single machine, it would take (assuming non-stop function)\n\n3000,000Kb/600Kb = 5000\n\nTherefore, given a top of the line machine, the human genome could be sequenced in forty thousand hours, or a little over 109 years. That's why they use a lot of machines to do sequencing... or just use small parts of a single Chromatid.
1020699
First of all make sure your template is good quality. Did you extract genomic DNA, do you have a library in plasmids...(?).\nTry re-purifying your template.\n\nMaybe your template is GC-rich or has some secondary structure.\nIs your template very long?If so make sure you let the polymerase is working at the elongating temperature for enough time (1min/kb)\n\nIf you are using plasmid template try not to use too much. Don't put more than 30-40ng DNA in a reaction. \n\nCheck your primers:\n-can they form a dimer?\n-can they anneal at more than one site on the template DNA with a only few mismatches?\n-is the difference in the Tm of the two primers more than 6 C (it shouldn't;ideally they should be the same and I try not to exceed a difference of 4)?\n-do your primers end in more than 3  c or g in a row?\n-what's their Tm and GC content?Tm should not be very low (I design my primers at 56-61) and GC 40-60%.\n\nThe most strigent conditions are using as annealing temperature 2 C below the lowest Tm of the two primers. Try lower temperatures.\n\nYou can try different enzymes Taq, Pfu, Pwo, etc, even mixtures. Not all enzymes have the same processivity.\n\nYou can try different Mg+2 concentrations.\n\nThere are a lot of control experiments you can do depending on your template and primers. Eg if you have a library in a  plasmid that has sites for universal primers you can use one such primer and the other respective primer you designed in order to check if there is something wrong with the quality of your primers. \n\nIf everything is perfectly designed and you've tried evreything but still get a very faint (but of correct size) band, gel purify it and use it as a template for a new PCR. In this case you'll have a very high chance of getting mutations so you'll need to use a high fidelity enzyme like Pwo or Pfu turbo and of course sequence a lot till you get a correct clone.
62320
well, hope these help:\n\nhttp://www.bbc.co.uk/dna/h2g2/A388217\n\nhttp://www.chemistrysurvival.com/
478939
I would call them "gene sequences" or even "coding sequences", rather than just "genes."\n\nIt depends how much you want to get into the molecular genetics. You could discuss which part of the sequence was composed of "introns" and which were "exons".\n\nIf you give a really technical answer to a teacher who is marking tests "by the (simple) book", they might mark it wrong; it has happened to me!
558138
Electrophoresis is a process used in molecular biology labs where a given protein, often of unknown composition, is migrated through a gel with polarity;positively charged on one side and negatively on another, such that the protein, in this case DNA, is migrated through the gel to create "bands" (visual horizontal lines).  The distance that the DNA fragment migrates is inversely proportional to the (log 10) of their molecular weight.  This enables the researcher to deduct the sequence of the codons within the particular DNA sequence and this is critical in mapping genes and sequencing.\n\nAgarose gel electrophoresis is an easy way to separate DNA fragments by their sizes and visualize them. It is a common diagnostic procedure used in molecular biological labs.\nThe technique of electrophoresis is based on the fact that DNA is negatively charged at neutral pH due to its phosphate backbone. For this reason, when an electrical potential is placed on the DNA it will move toward the positive pole (source:  http://www-biology.ucsd.edu/classes/bicd101.SP06/Electrophoresis_of_DNA.doc)\n\nSee this link for more info:\nhttp://www.vivo.colostate.edu/hbooks/genetics/biotech/gels/agardna.html
91642
- with PCR you amplify a DNA sequence (like ATGGTAGCATGATC etc etc etc)\n- P = polymerase (thats the name of the enzyme that does the amplification\n- C = chain (there are actually two chains: first the chain of nucleotides ATGGAGACCCTAetc and second the chain of polymerization reactions)\n- R = the enzymatic amplification reaction\n- you can only do a PCR with a DNA double strand, because you need two starter oligonucleotides that bind to the initial template that you want to amplify; they resemble a short DNA sequence of the complementary (opposite) strand; they work best when they have a length between 18 and 20 nucleotides. When you do a PCR, you will most likely know the sequence of these oligonucleotides and you will order them from a company who designs them for you (you just give them the sequence you desire and they make them fo you)\n- so when you do a PCR, you have to offer the polymerase enzyme some material so that it can work: i.e. the template DNA that you want amplified, the starter oligonucleotides and especially the single nucleotides A, T, G, C\n\n- for RFLP you will need an enzyme that cuts the DNA strand\n- restrictions enzymes cut specific sites\n- they have names like BamHI EcoRI etc etc etc\n- example: BamHI cuts at the site GGATCC and only there\n- so when you have a DNA sequence that is, say 2000 basepairs long, and you have only one GGATCC, the enzyme will cut only once. If the DNA sequence was linear (i.e. it has two ends like a sausage) then you will get 2 DNA fragments. If your DNA is circular, you will get one fragment\n- so think in larger dimensions: if you cut a tremendously long DNA sequnece, you will have more GGATCC sites, consequently you will get more fragments.\n- so if you know your sequence, you can just do your simple math calculations and predict the fragments and their lengths: from the fist GGATCC to the second its, for example 10,010 basepairs, from the second to the third xxx and so on\n\n- R = restriction (cutting the DNA strand into pieces)\n- F = fragment (the pieces of DNA that arise when cutting the large one)\n- L = length (the different lentgs of DNA pieces that arise during the cutting)\n- P = polymorphism (referring to the fragment pattern when comparing them to the pattern of different samples)\n- the actual RFLP comparisons are made in the gel, because sometimes you don't have the exact DNA sequence of every DNA you want to analyze\n- for example, you cut the genomic DNA of two or more related bacterial species. And lets say you will know the exact sequence of only one of them. For that one you can make predictions about fragment lengths based on your calculations. For the others you can't, because maybe they have mutations in their sequences.\n- so when you compare the fragments to each other and to the one you initially precalculated, you might find that the other related species reveal different fragments. That means the sequences af the repated species have alterations in the site where the restriction enzyme was supposed to cut.\n- So the interpretation will be that specific DNA sites have an altered sequence to the sequence that was given to you\n- you can also make predictions about total mutations in the DNA, if you know how long the total DNA was and if you know how many restrictions sites there are and how many were not cut with a specific enzyme
230683
I respectfully disagree with the previous answer.\n\nGranted, X-Ray crystallography was used to discover the structure of DNA, but it was not used to sequence DNA.  Educated guesswork would not come close to sequence some billions of base pairs.  What is used is a "shotgun" approach, developed by Craig Venter (I hope I spelled that right) of Celera Genomics.  Essentially, it sequences random fragments of DNA, and a computer puts these fragments together into a sequence.  \n\n1. Between two random humans, ~99.9% of their DNA sequence will align.  Aside from the fact that sequencing one person's DNA would be impractical, one person probably wouldn't represent a "human" genome particularly well.  A group of volunteers was actually used in the Human Genome Project.  In other words, the current sequence used today is not from one person, but from many people.\n\n2. The genome was sequenced not as a random series of G's, A's, C's, and T's (I guess in a way it was), but it was sequenced with the intent to study various functional units --genes.  Funnily enough, most people's genes are pretty much the same.  Even more odd is the fact that a human gene that codes for a particular protein is typically nearly identical to homologous genes in other species.  Some proteins that we have even have homologies with bacteria and plants!  (Conclusion: DNA sequences between humans, and even between species, like chimps, are really really similar)\n\n3. This is not to say that everyone's DNA are exactly identical, but they are close enough where groups of volunteers could be used.     \n\n4. Just in case you're curious, even though our DNA and a chimp's DNA are almost identical, I don't know about you, but I'm not a chimp.  The reason for this (and the focus of much biology research today) is how our genes are regulated versus how a chimp's genes are regulated.  \n\nSorry for the long answer, but I really like this stuff.  It's what I do.
520769
Good news: You won't need to read a whole book to get even losts of details as well as the basics: google for a "polymerase chain reaction faq" on the web. Its less complicated than you think. \n\n\nWant to spend less time commuting ? Check out http://www.hallisystem.bravehost.com  \nWrite us.
838778
To be honest with you i don't quite understand your question, it is often that restriction enzymes are used to create genomic library for which you look into the overlapping sequence and then be able to determine which fragment is next to which. If that is what you have done, you should have used the fragmented DNA sequence to determine the orginall DNA sequence that you digested it with the enzyme, to confirm the sequence you ahve found is correct, you can use PCR, you got the hypothetical sequence, thus by making primers from the start and the end of the sequence (doesn't matter which way round) you should have amplify the same sequence which you started with, you got the amplified DNA (same as the orginal DNA because you used primers that complemented the very start and the very end of the sequence which you found out after the restruction enzyme mapping) run it on gel electrophoresis with a DNA size marker that will include the size of DNA you have sequenced, if the amplified DNA size is the same as the sequence you have found from restriction mapping, that means your primers did complemented from the start and the end, that means the sequence you thought is actually the correct sequnece.\nI am sorry, i don't think i am making this clear enough, but anyway, that's the best i can think of.
401402
The base pair sequence is identical in every cell of a given human (barring oddities like chimeras).\n\nWhat differs is the genes that are active and inactive.  Sometimes base pair methylation is used for that; sometimes, binding of the DNA to histones or other protein (and probably RNA) molecules turn off or turn on genes, etc.  It's sort of like a piano--all the keys are there for every performance.  It's just that some are struck, and others not.  (And you'd probably rather listen to someone other than me playin' it...)  Depending on the order of the striking of the keys, and the combinations of keys struck at different times, you get different pieces of music.\n\nSimilarly the sequence and pattern of genes turned on and off generates different kinds of cells, even though the DNA is essentially identical.
297904
do a yahoo or google search on "gene sequence" Then look for what you want. Was it human genes?
432215
My guess would be dna sequencing.
84060
The base sequences in DNA are arranged in particular order along the sugar- phosphate backbone. The sequence specifies the exact genetic instructions required to create a particular organism with its own unique traits. \n\nThere are specific sequence of nucleotide bases, whose sequences carry the information required for constructing proteins, which provide the structural components of cells and tissues as well as enzymes for essential biochemical reactions.