Question

Restriction endonucleases will make two types of cuts, those that result in blunt ends (A) and ends with overhangs of one strand (B).
Based on the chemical characteristics of the fragment ends, predict which type of digest is more likely to happen?

• A. The blunt fragments are more likely because the re-annealing process is a seamless connection.
• B. The blunt fragments are more likely, because of complementarity of the adjoining fragments
• C. The overhang ends are more likely because the overhangs fit like two puzzle pieces.
• D. The overhang ends are more likely because of base complementarity leading to optimal hydrogen bonding.

Answer 1

The correct option is D The overhang ends are more likely because of base complementarity leading to optimal hydrogen bonding.

The ligation of blunt ends is more difficult to occur and requires high concentration of blunt end fragments that are to be ligated. High concentration of enzyme ligase, low concentration of ATP and PEG for ligation to occur. However, this can be easily achieved if the restriction enzymes cut the DNA with staggering ends, the ligation occurs naturally with other DNA fragments with complementary base pairs.Therefore, of the two types of cuts by different types of restriction enzymes, the sticky end cuts are more preferable over blunt ends.

So, the correct answer is 'The overhang ends are more likely because of base complementarity leading to optimal hydrogen bonding'