A Chimeric Plasmid Contains Vector DNA Ligated to a Fragment

Essay

A chimeric plasmid contains vector DNA ligated to a fragment of chromosomal mouse DNA that is suspected of containing the obese gene.As a first step,a restriction map of the DNA clone was constructed.The DNA was digested with two restriction enzymes,BopI and ZapII,with the following results:

a)From these data,answer the following questions.
(1)How large is the entire DNA clone?
(2)Is the clone linear or circular?
(3)Draw a restriction map consistent with these data.Include all BopI and ZapII sites and the physical distances between them.

b)To better identify the location of the mouse chromosomal DNA on this chimeric plasmid,mouse genomic DNA was digested with ZapII,run on a gel,and analyzed using the Southern blot technique.The Southern blot was probed with radiolabeled Zap II DNA fragments from the plasmid DNA.Three lanes each containing the same amount of Zap II-digested chromosomal DNA were each probed with a different fragment from the plasmid.Autoradiograms showed the following: What is the maximum amount of mouse DNA present in the clone? Why didn't the 2.0-kb ZapII fragment hybridize to the mouse DNA?