on the basis of band formed after electrophoresis how can we detect the dna whether it is linear or circular.
hi
if I understand your Question correctly I'll answer you:
for example we have 3 band in plasmid DNA preparation. first for linear DNA,second for circular DNA,,and third for superhelix circular DNA.so we can say that the circular DNA move faster than linear DNA in gel.
but for detect of this(linear from circular) we must pure the sample very very good!
best regards
I think you interested in DNA structure.the modelling and bioiformatic are better for these field.and the method of "single-molecule" is too useful.
this paper can help you:
"cellular Strategies for Regulating DNA supercoiling:A single-molecule perspective" 2010cell
Its simple to find the DNA is linear or circular by seeing the bands in gel electrophoresis. Circular DNA basically in coiled and will be in form of compressed rubber band, so it can easily pass through the pores in the gel.. But a linear DNA will get caught between the pores of the gel and wont able to move further. So the linear DNA will be found on the top or middle of the gel.. But due to free motility, the circular DNA will be found in the end of the gel.
If you run plasmid DNA on agarose gel and obtain 3 bands, then the topmost band will correspond to the open circular form of DNA (OC), the middle one will be of linear DNA and the one below that will correspond to Closed circular (CC) or Superhelical form of DNA... The separation is definitely on the basis of size and topology, i.e conformation of the molecules...
Sometimes a smear is seen, this reflects the fragmentation of the linearised DNA.
well, just use a control sample DNA
(circular or linear). Compare with your sample DNA. the linear usually have higher Mwt. on gel than circular.
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