Restriction endonucleases, often referred to as 'molecular scissors', cleave DNA molecules at specific recognition sites that typically exhibit which structural feature?
Answer and explanation
Correct answer: A. Palindromic sequences reading identically on both strands in the 5' to 3' direction
- Step 1: Restriction endonucleases are bacterial defense enzymes that cleave foreign bacteriophage DNA.
- Step 2: They recognize specific palindromic sequences ( long) where the sequence of base pairs reads identically in the direction on both antiparallel strands.
- Step 3: For example, EcoRI recognizes and cleaves between G and A, producing sticky, cohesive single-stranded overhangs.
Answer
Palindromic nucleotide sequences reading identically on both complementary strands in the direction.
Why not the others: Poly-A sequences are post-transcriptional mRNA tails, not restriction sites; Telomeres contain tandem repeats; Methylated CpG islands are epigenetic modifications that often block restriction enzymes.
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