why do scientists use the same enzyme to remove the insulin and cut the plasmid?
Scientists often use the same enzyme, called restriction endonuclease, to remove the insulin gene from its original DNA source and to cut the plasmid. This is because restriction endonucleases possess a specific property called site-specific recognition and cleavage.
The first step in this process involves cutting out the insulin gene from the original DNA source, which could be human DNA or any other source containing the gene of interest. Scientists choose a specific restriction endonuclease that recognizes and cuts the DNA sequence surrounding the insulin gene. This sequence is known as the recognition site or restriction site.
Once the insulin gene is removed, it needs to be inserted into a plasmid. Plasmids are small, circular DNA molecules commonly found in bacteria, and they serve as a common tool for genetic manipulation in the laboratory. To add the insulin gene to the plasmid, the plasmid needs to be cut open.
Using the same restriction endonuclease that was used to remove the insulin gene, scientists cut the plasmid at a specific location. This location is usually chosen to create a "sticky end" or overhang, which is compatible with the insulin gene's sticky end. These sticky ends are single-stranded DNA sequences that can form base pairs with complementary sticky ends.
By using the same restriction endonuclease, scientists ensure that both the insulin gene and the plasmid have compatible sticky ends. This allows for efficient and specific ligation or joining of the two DNA molecules using another enzyme called DNA ligase. The resulting plasmid with the insulin gene becomes a useful tool for producing insulin or studying its function.
In summary, scientists use the same enzyme, restriction endonuclease, to remove the insulin gene and cut the plasmid because it allows for efficient and specific DNA manipulation by generating compatible sticky ends for ligation.