Pieces of DNA ( please explain how you got the answers )

Question

This is a piece of DNA showing the sites in which restriction enzymes bind to and cut DNA into fragments, and the size of the DNA between the restriction enzyme sites.:

 

    2kb                4kb             3.5kb                5kb                2kb            2kb

 

  - - - - - A - - - - - - - - - - Y - - - - - - G - - - - - - - - - - - -K - - - - - -Y- - - - - - -

 

If the DNA were cut using enzyme G, what would be the sizes of the DNA fragments created?

 

If the DNA were cut using enzyme Y, what would be the sizes of the DNA fragments created?

 

Answer 1

Hi J,

 

It is an 18.5 kb linear fragment as depicted from map in your question.

 

Site G is almost in  middle and there is only one site G. Enzyme digestion would produce two fragments: 9.5 and 9 kb. 

they may run like a doublet in 0.6% agarose gel. The gel needs to be run very slowly and o/n for separation. On a standard 1% agarose gel, it would look like a single band.

 

Y enzyme has twp sites and it would produce three fragments: 10.5 kb, 6kb and 2.5 kb.  You can separate them on 1% agarose gel by running for about 3-4 hours. 10.5 kb band would be at very top. 

 

Best.