Which map shows enzyme E1 between E3 and E4?
Restriction maps order recognition sites along DNA by analyzing fragment overlaps from single and double digestions on agarose gels. If enzyme E1 lies physically between E3 and E4, digestion with E3 and E4 would generate fragment where E1 site resides entirely inside that interval, and triple digest would split that interval into two smaller pieces whose sizes sum to original. Correct map representation showing relative order helps predict fragment sizes for diagnostic digests and cloning strategies. Precise ordering is critical for designing double digests, assembling contigs, and interpreting RFLP polymorphisms in genetic analysis.
Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.