The result being both ends have a single stranded area called the sticky ends . It is within this space that the new piece of DNA is added, attaching to the sticky ends. See the diagram below. These unions are temporary until the enzyme DNA ligase is added to catalyze the formation of the phosphodiester bonds. Bacterial plasmids and viruses are the most widely used vectors in DNA transfer.
Bacterial cells can pick up the DNA through the process of transformation.
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.