Q.14 Restriction endonucleases which recognize and cut same recognition sequences are known as
- (A) isoschizomers
- (B) isozymes
- (C) isoaccepting endonucleases
- (D) abzymes
Restriction endonucleases that recognize and cut the same recognition sequences are known as isoschizomers. This SEO-optimized article answers the MCQ: Restriction endonucleases which recognize and cut same recognition sequences are known as (A) isoschizomers, (B) isozymes, (C) isoaccepting endonucleases, (D) abzymes—essential for molecular biology, genetic engineering, and biotechnology exam preparation.
Correct Answer: Option (A) Isoschizomers
Isoschizomers are restriction enzymes from different bacterial species that recognize identical DNA sequences and cleave at the same positions. Examples include MboI and Sau3AI (both cut ^GATC) or EcoRI and its isoschizomers like SseAI.
Discovered post-1970s, isoschizomers enable methylation sensitivity analysis (e.g., HpaII vs. MspI for CCGG), crucial for epigenetics and cloning strategies in your genetic engineering work.
Explanation of All Options
Each term describes enzyme variants but applies differently:
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(A) Isoschizomers: Correct. Same recognition sequence + same cut site (e.g., SphI = BbuI = CGTA^CG).
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(B) Isozymes: Incorrect. Multiple enzyme forms catalyzing identical reactions with different structures (e.g., LDH isoforms), not DNA-specific.
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(C) Isoaccepting endonucleases: Incorrect. Term applies to tRNAs accepting same amino acid; no standard usage for restriction enzymes.
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(D) Abzymes: Incorrect. Catalytic antibodies engineered to mimic enzymes, not natural restriction endonucleases.
Option Definition Applies to Restriction Enzymes? Example Correct/Incorrect (A) Isoschizomers Same sequence + cut site Yes MboI = Sau3AI (^GATC) Correct (B) Isozymes Same reaction, different proteins No Alkaline phosphatases Incorrect (C) Isoaccepting Same tRNA specificity No tRNA-Val variants Incorrect (D) Abzymes Catalytic antibodies No Anti-hapten antibodies Incorrect Biotechnology Applications
Isoschizomers facilitate complete/partial digests, methylation mapping (bisulfite-independent), and vector compatibility in cloning—vital for YACs (Q.4), hairy roots (Q.11), and synthetic seeds transformation systems you’ve studied.
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