You are working in a medical research lab and have to determine if a patient is heterozygous or homozygous for a particular restriction site. You isolate a region of DNA from each chromosome, the middle of which could contain the restriction site, if the patient has it. If you treat the DNA with the restriction enzyme, how many fragments will be produced if the patient is heterozygous for the presence of the restriction site?

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Quizplus · Accepted Answer

If the patient is heterozygous for the presence of the restriction site, one chromosome will have the restriction site and the other will not. Treating the DNA with the restriction enzyme will cut the chromosome with the restriction site into two fragments, while the chromosome without the restriction site will remain intact. Therefore, there will be three fragments in total: two from the chromosome with the restriction site and one from the chromosome without it.

You Are Working in a Medical Research Lab and Have