In genetic engineering, what is the purpose of ligating DNA fragments?

• A. To separate DNA molecules
• B. To join DNA fragments for cloning or analysis
• C. To degrade unwanted DNA
• D. To amplify a specific gene

Answer: (B)

Ligation is a critical step in genetic engineering that involves the joining of DNA fragments, typically facilitated by an enzyme called DNA ligase. This process is essential for creating recombinant DNA, which combines DNA from different sources. The primary purpose of ligating DNA fragments is to ensure that these fragments can be appropriately linked together to form a continuous DNA strand, necessary for successful cloning, expression, or further genetic analysis.

In cloning applications, for instance, ligating a DNA fragment containing a gene of interest into a plasmid vector allows for the introduction of that gene into host cells. This enables the gene to be replicated and expressed, facilitating the study of its function or production of its corresponding protein. Thus, the ability to join DNA fragments through ligation is foundational to numerous techniques in genetic engineering and biotechnology, enabling researchers to manipulate genetic material effectively.