Lambda phages are used by eliminating the middle of its liner genome and adding the foreign DNA in the created space. The phage is then introduced into the bacterial cell where it replicated itself via the lysogenic cycle. Bacteria are usually used as hosts in genetic engineering. There are several reasons why they are chosen. Bacterial DNA can be easily isolated and reintroduced into bacterial cells.
Bacterial cultures grow quickly.
Bacteria, being prokaryotic, may not be able to use the information in eukaryotic genes. Bacterial cells cannot make the the necessary changes in transcription to produce some eukaryotic proteins. Eukaryotic cells can also be used as hosts. Treatment of plasmid and foreign DNA with the same restriction enzyme. Mixture of foreign DNA with clipped plasmids.