In Cell-Based DNA Cloning Two Types of Enzyme Are Critical

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The Answer is 1) A class II restriction endonuclease. Enzymes like this recognize short specific sequences, usually spanning a region of 4-8 nucleotides long, and then cut the DNA on both strands, either within this sequence or in the immediate vicinity. As a result of their sequence specificity, they allow cutting of the DNA at specific sites. The restriction endonuclease that is chosen for use is one that is designed to cut the vector molecule at a unique location to produce defined ends. The DNA to be cloned is often a heterogeneous collection of very large DNA fragments with heterogeneous ends, but by cutting with a specific restriction nuclease the DNA population is reduced to DNA fragments that are both of manageable size and also have homogeneous ends that are compatible with the ends of the cut vector, allowing relatively easy joining of the cut vector to the DNA fragments.
2) A DNA ligase. Needed to covalently join the cut vector molecule to the DNA fragments produced by cutting the DNA sample with a restriction endonuclease.

In Cell-Based DNA Cloning Two Types of Enzyme Are Critical

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