A fragment of DNA containing the gene to be cloned is inserted into a circular DNA molecule called a vector, and to produce a recombinant DNA molecule.
The vector transports the gene into a host cell, which is usually a bacterium, although other types of living cells can be used.
Within the host cell, the vector multiplies and it produces numerous identical copies, not only of itself but also of the gene that it carries.
When the host cell divides then the copies of the recombinant DNA molecule are passed to the progeny and further, the vector replication takes place.
After a large number of cell divisions, a colony and or a clone of identical host cells is produced.
Each cell in the clone contains one or more copies of the recombination DNA molecule.
The gene carried by the recombinant molecule is now said to be as cloned.