Question

In RFLP, ladders are electrophoresed_________________.

And thus, permit the use of probe hybridization.
		To allow for visualization of the fragments.
		To determine the length of VNTRs.
		To ensure proper separation of VNTRs of interest.
		None of the above

Answer 1

In RFLP, ladders are electrophoresed to determine the length of VNTRs. And thus, permit the use of probe hybridization.

Explanation:

Every individual has a 0.1% of unique distribution of the sequences and hence has a variations in the restriction-site sequences distribution making it specific for an individual.

A specific type of restriction endonuclease will cut the DNA molecule into a set of fragments of various sizes according to the site distribution in that particular person's DNA sample. This forms a restriction pattern and acts a molecular marker.

If two samples of DNA from different individuals are subjected to the same restriction enzyme digestion will create two different restriction patterns which will be dependent on the variation in the DNA sequence and number and distribution of the restriction sites of that particular enzyme used.

The DNA fragments formed due to digestion can be separated out by agarose gel electrophoresis technique based on their molecular weight.

While performing agarose gel electrophoresis, DNA ladder of known molecular-weight size marker should be run simultaneously on the same gel to determine the fragment band sizes of the unknown sample fragments and compare with the known DNA ladder.

On the basis of the known specific sequence a molecular probe can be designed which hybridizes with one or more fragments after the agarose gel electrophoresis separation. resulting into a unique blotting pattern characteristic to a specific genotype at a particular locus.