OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What enzyme is used to cut out the insulin gene from human DNA?

1. Polymerase

2. Ligase

3. Restriction enzyme

4. Amylase

The correct answer is: Restriction enzyme

The enzyme that is used to cut out the insulin gene from human DNA is a restriction enzyme. Restriction enzymes are specialized proteins that act like molecular scissors, recognizing specific sequences of nucleotides in DNA and cleaving the strands at those sites. This property enables scientists to isolate particular genes, such as the insulin gene, for cloning or other genetic engineering purposes. In the context of insulin production, the process of cutting out the insulin gene allows researchers to insert it into plasmids or other vectors, which can then be introduced into bacteria or other cells for mass production of insulin. Restriction enzymes are crucial in genetic manipulation, enabling precise modifications of DNA. The other options do not serve this specific function. Polymerase is primarily involved in DNA replication, ligase connects DNA fragments together, and amylase breaks down carbohydrates, none of which directly relate to the process of excising a specific gene from DNA.