A molecular biologist is preparing to insert a gene of interest into a plasmid vector for bacterial expression. Which of the following best describes the primary role of restriction enzymes in this molecular cloning process?
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The answer
Correct answer: C. They cleave DNA at specific palindromic recognition sequences, generating ends suitable for ligation into a vector.
Tested concept: Restriction enzymes and cloning
Explanation
Restriction enzymes, also known as restriction endonucleases, are crucial tools in molecular cloning. Their primary function is to recognize and cleave DNA at specific nucleotide sequences, often palindromic. This cleavage generates DNA fragments with either 'sticky' (overhanging) or 'blunt' ends. These ends are essential because they provide compatible sites for the gene of interest and the plasmid vector to be joined together by DNA ligase, forming recombinant DNA. The option stating that they facilitate the unwinding of the DNA double helix describes the function of helicase. The option stating that they catalyze the formation of phosphodiester bonds describes the function of DNA ligase. The option stating that they synthesize complementary DNA strands describes the function of DNA polymerase or reverse transcriptase, not restriction enzymes.
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