Final answer:
The normal beta-globin allele with the sequence CCTGAGGAG contains the DdeI recognition sequence and would be cut by the enzyme, whereas the sickle-cell allele with the sequence CCTGTGGAG does not contain this site due to the mutation.
Step-by-step explanation:
The question involves analyzing DNA sequences to determine which allele would be cut by the restriction enzyme DdeI, which has a recognition sequence of CTNAG ('N' indicates any base). The mutation in the sickle-cell allele replaces a GAG sequence with a GTG, losing the DdeI site present in the normal beta-globin allele. The normal beta-globin allele has the sequence CCTGAGGAG, which includes the DdeI recognition sequence CTGAG. Therefore, the normal allele would be the one cut by DdeI, as the sickle-cell allele's sequence CCTGTGGAG lacks this site due to the base substitution that causes sickle-cell anemia.
The normal beta-globin allele contains the sequence CCTGAGGAG, while the mutant beta-globin allele contains the sequence CCTGTGGAG. The restriction enzyme DdeI cuts at the sequence CTNAG where N is any base. Therefore, in the normal beta-globin allele, the sequence CCTGAGGAG contains the recognition site CTGAG, which matches the cut site of DdeI. However, in the mutant beta-globin allele, the sequence CCTGTGGAG contains the recognition site CTGTA, which does not match the cut site of DdeI. Therefore, the restriction enzyme DdeI would cut the normal beta-globin allele, but not the mutant beta-globin allele.