The DNA for the normal hemoglobin allele and the mutant sickle-cell allele are cut with the same restriction enzyme,DdeI.The resulting DNA fragments are separated by gel electrophoresis,producing the gel shown in the following figure.Why are the patterns produced by these two alleles different?

A) The normal hemoglobin gene is cut by two restriction enzymes,but the sickle-cell anemia allele is cut by only one restriction enzyme.
B) The gene for the normal allele is much larger than the gene for sickle-cell anemia.
C) The gene for the normal allele has a sequence recognized by DdeI,but the gene for sickle-cell anemia does not.
D) The sickle-cell allele has the ability to produce ligase to repair the damage done by restriction enzymes,but the normal allele does not.

Question

The DNA for the normal hemoglobin allele and the mutant sickle-cell allele are cut with the same restriction enzyme,DdeI.The resulting DNA fragments are separated by gel electrophoresis,producing the gel shown in the following figure.Why are the patterns produced by these two alleles different?

A) The normal hemoglobin gene is cut by two restriction enzymes,but the sickle-cell anemia allele is cut by only one restriction enzyme. 
B) The gene for the normal allele is much larger than the gene for sickle-cell anemia. 
C) The gene for the normal allele has a sequence recognized by DdeI,but the gene for sickle-cell anemia does not. 
D) The sickle-cell allele has the ability to produce ligase to repair the damage done by restriction enzymes,but the normal allele does not.

Quizplus · Accepted Answer

The patterns produced by the normal hemoglobin allele and the sickle-cell allele are different because the normal hemoglobin gene has a sequence that is recognized by the restriction enzyme DdeI, but the sickle-cell anemia allele does not. Therefore, the normal hemoglobin gene will be cut at this restriction site, producing two fragments of predictable sizes, while the sickle-cell allele will remain uncut, producing a single large fragment.

The DNA for the Normal Hemoglobin Allele and the Mutant