The color of DNA strands that come out of the capillary can be correlated to DNA sequence because?

A) the capillary has sorted the dna strand so they come out in order, with each being exactly on the base longer than the previous strand


B) all of the DNA strands are colored with dye


C)DNA strands are sorted so that the long strands come out first


D) none of the above

The color of DNA strands that come out of the capillary can be correlated to DNA sequence because?
Ah! you want to know how the automated DNA sequencing works. B is certainly true, they are tagged with 4 different fluorescent dyes, one for each base A, C, G, T. I would have to look up the rest...specifics might depend on exactly which machine or method you are using, but the fluorescent dyes are a substitute for radiolabeling. Some run the DNA through a gel or other medium (size separation assay) others read the color directly in the tube. If some are coming out first, you're probably doing some size separation. If it ran through a gel, the shortest ones came out first, so C is most likely false. It's not really clear what assay you are running...otherwise I'd tell you more.
Reply:B
Reply:I'd have to say A, since it is the basis of automated sequencing. If the DNA is replicated in the presence of fluorescence-labeled nucleotides, they will be incorporated into the strand (eliminating the need to stain them with a dye - which would be very difficult in this case). The result will be a strand of DNA with each type of nucleotide labeled with a different color.


A fluorometer can measure the products coming out of the capillary, as they emerge. Since each fragment is one base longer than the previous one, by reading the colors that come out, you can determine each nucleotide in sequence.
Reply:I say C