Question

Which allele would be cut by the restriction enzyme DdeI, which cuts at the sequence CTNAG, where N is any base?

1) The β–globin allele responsible for sickle–cell anemia
2) The normal β–globin allele
3) Both alleles
4) Neither allele

Answer 1

The DdeI enzyme would cut the normal β–globin allele but not the β–globin allele responsible for sickle–cell anemia.

Step-by-step explanation:

The restriction enzyme DdeI recognizes and cuts at the sequence CTNAG, where N is any base. In the case of the β–globin allele responsible for sickle–cell anemia, the DNA sequence is CCTGTGG, which contains the recognition sequence CCTNAGG. Therefore, this allele would not be cut by the DdeI enzyme.

On the other hand, in the normal β–globin allele, the DNA sequence is CCTGAGG, which also contains the recognition sequence CCTNAGG. Hence, this allele would be cut by the DdeI enzyme.

In summary, the DdeI enzyme would cut the normal β–globin allele, but it would not cut the β–globin allele responsible for sickle–cell anemia.