Restriction endonucleases recognize specific

Restriction endonucleases recognize specific

• A. Random DNA sequences
• B. Palindromic DNA sequences
• C. Guanine-rich regions
• D. AT-rich regions

Answer: (B)

Restriction enzymes bind to specific DNA sequences that are palindromic. A palindromic sequence reads the same in the opposite direction on the complementary strand, which fits the dimeric nature of many restriction enzymes that have two active sites—one on each subunit—to cut both strands in a coordinated way. For example, EcoRI recognizes GAATTC, and this sequence is identical to its reverse complement (GAATTC), so the enzyme can engage symmetrically with both strands and cleave precisely at that site. Random DNA sequences would not provide the precise, reproducible binding that these enzymes need. GC-rich or AT-rich regions describe base composition, not a specific recognition motif; while some enzymes may have preferences, the classic and most common recognition patterns for restriction enzymes are palindromic sequences.

Restriction enzymes bind to specific DNA sequences that are palindromic. A palindromic sequence reads the same in the opposite direction on the complementary strand, which fits the dimeric nature of many restriction enzymes that have two active sites—one on each subunit—to cut both strands in a coordinated way. For example, EcoRI recognizes GAATTC, and this sequence is identical to its reverse complement (GAATTC), so the enzyme can engage symmetrically with both strands and cleave precisely at that site.

Random DNA sequences would not provide the precise, reproducible binding that these enzymes need. GC-rich or AT-rich regions describe base composition, not a specific recognition motif; while some enzymes may have preferences, the classic and most common recognition patterns for restriction enzymes are palindromic sequences.