Question

Plasmid is a boon to biotechnology. Justify this statement quoting the production of human insulin as an example.

Answer 1

Plasmids are small circular extra-chromosomal DNA molecules that act as vectors.

Why they are a boon:

1. They are easily isolated and small in size. 
2. They have an origin of replication (ori), giving multiple copies of the gene. 
3. They carry selectable markers (ampR, tetR) to identify transformed cells. 
4. They have unique cloning sites for restriction enzymes. 

Example: For human insulin, the A and B chain genes were inserted into plasmid pBR322 and transferred into E. coli. The bacteria then produced insulin chains, which were combined to form active human insulin.

Plasmids made large-scale production of safe human insulin possible.