Q45 / 200 · MHT CET - Medical 2026 (24 April Shift 1) · Biology
The restriction endonuclease responsible for cleaving the given restriction site is ___________.
- Correct answerAAlu I
- BBam HI
- CEco RI
- DHind II
Solution
The given image shows a DNA sequence with a recognition site of $5'-\text{AGCT}-3'$ on the top strand and $3'-\text{TCGA}-5'$ on the bottom strand. The arrows indicate that the cleavage occurs between the guanine (G) and cytosine (C) bases, producing blunt ends.
Let us evaluate the recognition sequences and cleavage sites of the given restriction endonucleases:
Alu I: Recognizes the tetranucleotide sequence $5'-\text{AGCT}-3'$ and cleaves between G and C, producing blunt ends.
Bam HI: Recognizes $5'-\text{GGATCC}-3'$ and cleaves between G and G, producing sticky ends.
Eco RI: Recognizes $5'-\text{GAATTC}-3'$ and cleaves between G and A, producing sticky ends.
Hind II: Recognizes $5'-\text{GTYRAC}-3'$ (where Y is a pyrimidine and R is a purine) and cleaves in the middle, producing blunt ends.
The sequence and cleavage pattern shown in the image exactly match the restriction endonuclease Alu I.
Answer: Alu I
Let us evaluate the recognition sequences and cleavage sites of the given restriction endonucleases:
Alu I: Recognizes the tetranucleotide sequence $5'-\text{AGCT}-3'$ and cleaves between G and C, producing blunt ends.
Bam HI: Recognizes $5'-\text{GGATCC}-3'$ and cleaves between G and G, producing sticky ends.
Eco RI: Recognizes $5'-\text{GAATTC}-3'$ and cleaves between G and A, producing sticky ends.
Hind II: Recognizes $5'-\text{GTYRAC}-3'$ (where Y is a pyrimidine and R is a purine) and cleaves in the middle, producing blunt ends.
The sequence and cleavage pattern shown in the image exactly match the restriction endonuclease Alu I.
Answer: Alu I
Hence, the correct answer is option: 'A'.