Q.32 Recognition sequence of Restriction Endonuclease : BamH1 is
1. —AAGCTA—
—TTCGAT—
2. —GGATCC—
—CCTAGG—
3. —GTACAG—
—CATGTC—
4. —AGATCA—
—TCTAGT—
BamHI is a type II restriction endonuclease from Bacillus amyloliquefaciens that recognizes a specific palindromic DNA sequence, cleaving it to produce sticky ends essential for molecular cloning.
Correct Answer
2. —GGATCC—
—CCTAGG—
This is BamHI’s canonical 6-base pair recognition site (5′-GGATCC-3′), cut between the two G’s on each strand, generating 5′-GATC overhangs for ligation compatibility.
Option Analysis
Option 1: —AAGCTA— / —TTCGAT—
This is MseI‘s site (or Sau3AI-like); not palindromic for BamHI and lacks the GGATCC motif—no cleavage by BamHI.
Option 2: —GGATCC— / —CCTAGG—
Correct: BamHI’s precise palindromic sequence, widely used in recombinant DNA tech for precise fragment insertion.
Option 3: —GTACAG— / —CATGTC—
Resembles PstI or non-standard sites; mismatched bases prevent BamHI binding due to strict sequence specificity.
Option 4: —AGATCA— / —TCTAGT—
Similar to BclI but inverted; no GGAT match, so BamHI ignores it entirely.
| Option | Sequence (5′-3’/3′-5′) | Enzyme Match | Cleavage Type |
|---|---|---|---|
| 1 | AAGCTA / TTCGAT | MseI | Blunt |
| 2 | GGATCC / CCTAGG | BamHI | Sticky |
| 3 | GTACAG / CATGTC | PstI-like | None |
| 4 | AGATCA / TCTAGT | BclI-like | None |
Clinical Relevance
Mastering BamHI’s sequence is crucial for biotech exams (e.g., CSIR-NET, GATE) and lab work in cloning vectors like pBR322.
