When a typical restriction enzyme cuts a DNA molecule, the cuts are staggered so that the DNA fragments have single-stranded ends. This is important in recombinant DNA work because __________.

• A. it allows a cell to recognize fragments produced by the enzyme
• B. the single-stranded ends serve as starting points for DNA replication
• C. it enables researchers to use the fragments as introns
• D. only single-stranded DNA segments can code for proteins
• E. the fragments will bond to other fragments with complementary single-stranded ends

Answer: (E)

Verified step by step guidance

1. Understand the role of restriction enzymes: Restriction enzymes are proteins that cut DNA at specific sequences, often creating staggered cuts that result in single-stranded overhangs or 'sticky ends'.
2. Recognize the significance of sticky ends: These single-stranded overhangs are crucial because they can form hydrogen bonds with complementary sequences on other DNA fragments, facilitating the joining of different DNA pieces.
3. Consider the context of recombinant DNA technology: In recombinant DNA work, scientists often need to combine DNA from different sources. Sticky ends make it easier to ligate, or join, these fragments together, as they naturally seek out and bond with complementary sequences.
4. Evaluate the options given in the problem: The correct answer should relate to the ability of these fragments to bond with other DNA fragments, which is essential for constructing recombinant DNA molecules.
5. Conclude with the correct answer: The staggered cuts and resulting sticky ends are important because they allow the DNA fragments to bond with other fragments that have complementary single-stranded ends, facilitating the creation of recombinant DNA.