Q.31 Which one of the following restriction endonucleases is a blunt cutter?
(A) BamHI
(B) EcoRI
(C) HindIII
(D) EcoRV

EcoRV is the blunt cutter among the given options.

Question Breakdown

Restriction endonucleases cut DNA at specific recognition sequences, producing either sticky ends (staggered cuts with overhangs) or blunt ends (straight cuts with flush ends). Blunt cutters cleave both strands at the same position within the palindromic site.

Option Analysis

• (A) BamHI: Recognizes 5′-GGATCC-3′ and cuts after the first G on each strand (G^GATCC), generating 5′-GATC sticky ends.

• (B) EcoRI: Recognizes 5′-GAATTC-3′ and cuts after G (G^AATTC), producing 5′-AATT sticky ends.

• (C) HindIII: Recognizes 5′-AAGCTT-3′ and cuts after the first A (A^AGCTT), creating 5′-AGCT sticky ends.

• (D) EcoRV: Recognizes 5′-GATATC-3′ and cuts exactly in the middle (GAT^ATC), yielding blunt ends with no overhangs.

Correct Answer: (D) EcoRV

Introduction to Restriction Endonucleases Blunt Cutter

Restriction endonucleases blunt cutter enzymes are essential tools in molecular biology, precisely cleaving DNA at palindromic sequences. Unlike sticky end producers, a blunt cutter like EcoRV generates flush ends ideal for certain cloning strategies. This guide analyzes BamHI, EcoRI, HindIII, and EcoRV to identify the true restriction endonucleases blunt cutter for CSIR NET aspirants.

Recognition Sites and Cut Types

Each enzyme targets a 6-bp palindromic sequence but differs in cleavage position.

EcoRV stands out as the restriction endonucleases blunt cutter, slicing both strands centrally without overhangs.

Applications in Genetic Engineering

Blunt cutters like EcoRV enable ligation with any compatible end, though less efficiently than sticky ends from BamHI or EcoRI. Sticky ends facilitate directional cloning, while blunt ends suit linker addition or PCR product insertion. For CSIR NET, understanding these distinctions is key for questions on recombinant DNA technology.