What are the steps involved in genetic engineering?

Genetic engineering aims at synthesizing recombinant DNA which contains DNA from two different sources. Steps include:

1. Acquire gene of interest
2. Use molecular scissors to cut out the gene of interest. These are restriction endonucleases which cut gene at a site called palindromic sequences. 20 such enzymes are used extensively.     E.g. EcoR1.
3. Molecular vector or carrier on which gene if interest could be placed. It can be bacterial plasmid or viruses
4. The gene of interest along with the vector is then introduced into an expression system, as a result of a specific product is made.
5. A small piece of circular DNA called a plasmid is extracted from the bacteria or yeast cell.
6. A small section is then cut out of the circular plasmid by restriction enzymes, molecular scissors.
7. The gene for human insulin is inserted into the gap in the plasmid. This plasmid is now genetically modified.
8. The genetically modified plasmid is introduced into a new bacteria or yeast cell.
9. This cell then divides rapidly and starts making insulin.
10. To create large amounts of the cells, the genetically modified bacteria or yeast are grown in large fermentation vessels that contain all the nutrients they need. The more the cells divide, the more insulin is produced.
11. When fermentation is complete, the mixture is filtered to release the insulin.
12. The insulin is then purified and packaged into bottles and insulin pens for distribution to patients with diabetes.