Editing Cloning vector (section)

===Bacteriophage===
The bacteriophages used for cloning are the [[Bacteriophage lambda|λ phage]] and [[M13 phage]].<ref>{{cite journal | vauthors = Chauthaiwale VM, Therwath A, Deshpande VV | title = Bacteriophage lambda as a cloning vector | journal = Microbiological Reviews | volume = 56 | issue = 4 | pages = 577–591 | date = December 1992 | pmid = 1480110 | pmc = 372889 | doi = 10.1128/mr.56.4.577-591.1992 }}</ref>  There is an upper limit on the amount of DNA that can be packed into a phage (a maximum of 53 kb), therefore to allow foreign DNA to be inserted into phage DNA, phage cloning vectors may need to have some non-essential genes deleted, for example the genes for [[lysogeny]] since using phage λ as a cloning vector involves only the lytic cycle.<ref>{{cite book | vauthors = Glick BR, Pasternak JJ |year=2005 |title=Molecular Biotechnology Principles and Applications of Recombinant DNA |edition=3rd |publisher=ASM Press |url= https://books.google.com/books?id=Wz3CtTBe9aUC&pg=PA86 |isbn=9781555816124 }}</ref>  There are two kinds of λ phage vectors - insertion vector and replacement vector.  Insertion vectors contain a unique cleavage site whereby foreign DNA with size of 5–11 kb may be inserted.   In replacement vectors, the cleavage sites flank a region containing genes not essential for the lytic cycle, and this region may be deleted and replaced by the DNA insert in the cloning process, and a larger sized DNA of 8–24 kb may be inserted.<ref name = "Casali_2003" />

There is also a lower size limit for DNA that can be packed into a phage, and vector DNA that is too small cannot be properly packaged into the phage.  This property can be used for selection - vector without insert may be too small, therefore only vectors with insert may be selected for propagation.<ref>{{cite book |title=Gene Cloning and DNA Analysis: An Introduction|author= TA Brown|publisher=Wiley-Blackwell |page=100 |isbn= 978-1444334074 |url= https://books.google.com/books?id=Ju8XeJL9Fc4C&pg=PA100 |date= 2010-04-19}}</ref>