(c) Given the DNA shown below …
3’ ATTGAGGATCCGTAATGTGTCCTGATCACGCTCCACG 5’
5’ TAACTCCTAGGCATTACACAGGACTAGTGCGAGGTGC 3’
i) If this DNA was cut with BamHI, how many DNA fragments would you expect? Write out the sequence of these double-stranded DNA fragments.
ii) If the DNA shown in (c) was cut with BclI, how many DNA fragment would you expect? Write out the sequence of these double-stranded DNA fragments.
To determine the number and sequence of DNA fragments resulting from digestion with restriction enzymes, we need to first identify the recognition sites for the particular enzymes in the given DNA sequence.
i) BamHI is a restriction enzyme that recognizes the palindromic sequence 5' - GGATCC - 3'. By examining the given DNA sequence, we can identify that the recognition site for BamHI occurs at the position:
3’ ATTGAGGATCCGTAATGTGTCCTGATCACGCTCCACG 5’
↑
5’ TAACTCCTAGGCATTACACAGGACTAGTGCGAGGTGC 3’
This indicates that the sequence 5' - GGATCC - 3' is present in the DNA.
Cutting the DNA at this recognition site would result in two DNA fragments. The sequence of the double-stranded DNA fragments would be:
Fragment 1: 3’ ATTGAGGATCCGTAATGTGTCCTGATCAC 5’
Fragment 2: 5’ TAACTCCTAGGCATTACACAGGACTAGTGCGAGGTGC 3’
ii) BclI is another restriction enzyme that recognizes the palindromic sequence 5' - TGATCA - 3'. By examining the given DNA sequence, we can identify that the recognition site for BclI occurs at the position:
3’ ATTGAGGATCCGTAATGTGTCCTGATCACGCTCCACG 5’
↑
5’ TAACTCCTAGGCATTACACAGGACTAGTGCGAGGTGC 3’
This indicates that the sequence 5' - TGATCA - 3' is also present in the DNA.
Cutting the DNA at this recognition site would result in two DNA fragments. The sequence of the double-stranded DNA fragments would be:
Fragment 1: 3’ ATTGAG 5’
Fragment 2: 5’ TAACTCCTAGGCATTACACAGGACTAGTGCGAGGTGC 3’
Therefore, when the DNA in (c) is cut with BamHI, two DNA fragments are expected, while cutting with BclI would also yield two DNA fragments.