Molecular comparison tools: What do restriction maps allow researchers to do when analyzing DNA molecules?

Introduction / Context:
Restriction mapping is a classical molecular biology method to compare DNA fragments based on patterns of restriction enzyme cut sites. It predates routine DNA sequencing yet remains useful for quick assessments of plasmid identity, insert orientation, or recombinant integrity.

Given Data / Assumptions:

• Restriction enzymes cut at specific short recognition sequences.
• Fragments are separated by gel electrophoresis to create a banding pattern.
• We are comparing overall structure, not reading base-by-base sequence.

Concept / Approach:
A restriction map catalogs the positions of cut sites along a DNA molecule. If two DNAs produce identical fragment sizes with the same enzymes, they are likely the same or very similar constructs. This allows comparison without determining exact nucleotide sequences, saving time and cost in many routine workflows.

Step-by-Step Solution:
Digest DNA samples with one or more restriction enzymes.Run fragments on agarose or polyacrylamide gels to resolve sizes.Compare banding patterns across samples to infer similarity or differences.Conclude: restriction maps enable comparison without sequencing.

Verification / Alternative check:
Sequencing confirms the exact sequence but is not required for many screening tasks. Concordant restriction patterns across multiple enzymes provide strong evidence of construct identity.

Why Other Options Are Wrong:

• Requires sequencing (B): incorrect; mapping specifically avoids sequencing.
• Does not allow comparison (C): contradicted by routine lab practice.
• None of the above (D): incorrect since A is correct.

Common Pitfalls:
Misinterpreting partial digests or star activity; always include controls and, if needed, use multiple enzymes to increase confidence.

Final Answer:
allows comparison between DNA molecules without the need to determine nucleotide sequence