Editing Lambda phage (section)

==Anatomy==
[[File:Phage lambda virion.svg|thumb|250px|alt=The bacteriophage lambda virion | Bacteriophage lambda virion (schematic). Protein names and their copy numbers in the virion particle are shown. The presence of the L and M proteins in the virion is still unclear.<ref name="Raja_lambda">{{cite journal | vauthors = Rajagopala SV, Casjens S, Uetz P | title = The protein interaction map of bacteriophage lambda | journal = BMC Microbiology | volume = 11 | pages = 213 | date = September 2011 | pmid = 21943085 | pmc = 3224144 | doi = 10.1186/1471-2180-11-213 | doi-access = free }}</ref>]]

The virus particle consists of a head and a tail that can have tail fibers. The whole particle consists of 12–14 different proteins with more than 1000 protein molecules total and one DNA molecule located in the phage head. However, it is still not entirely clear whether the L and M proteins are part of the virion.<ref name="Raja_lambda" /> All characterized [[lambdoid phage]]s possess an N protein-mediated transcription antitermination mechanism, with the exception of phage HK022.<ref name="src3">{{cite journal | vauthors = Casjens SR, Hendrix RW | title = Bacteriophage lambda: Early pioneer and still relevant | journal = Virology | volume = 479-480 | pages = 310–330 | date = May 2015 | pmid = 25742714 | pmc = 4424060 | doi = 10.1016/j.virol.2015.02.010 }}</ref>
[[File:LambdaPhage Genome Linear.svg|thumb|498 px|center|Linear layout of lambda phage genome with major operons, promoter regions and capsid coding genes.<ref name="Raja_lambda"/>]]

The [[genome]] contains 48,502<ref>{{cite web | url=https://www.ncbi.nlm.nih.gov/nuccore/215104 | title=Escherichia phage Lambda, complete genome | date=6 January 2020 }}</ref> base pairs of double-stranded, linear DNA, with 12-base single-strand segments at both 5' ends.<ref name="CampbellPhage">{{cite book | vauthors = Campbell AM | chapter = Bacteriophages | veditors = Neidhardt FC, Curtiss R | date = 1996 | title = ''Escherichia coli'' and ''Salmonella typhimurium'': Cellular and Molecular Biology | publisher = ASM Press | location = Washington, DC | oclc = 1156862867 }}</ref> These two single-stranded segments are the "sticky ends" of what is called the ''cos'' site. The ''cos'' site circularizes the DNA in the host cytoplasm. In its circular form, the phage genome, therefore, is 48,502 base pairs in length.<ref name="CampbellPhage"/>  The lambda genome can be inserted into the '' E. coli'' chromosome and is then called a prophage. See section below for details.
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The tail of lambda phages is made of at least 6 proteins (H, J, U, V, Stf, Tfa) and requires 7 more for assembly (I, K, L, M, Z, G/T). This assembly process begins with protein J, which then recruits proteins I, L, K, and G/T to add protein H. Once G and G/T leave the complex, protein V can assemble onto the J/H scaffold. Then, protein U is added to the head-proximal end of the tail. Protein Z is able to connect the tail to the head. Protein H is cleaved due to the actions of proteins U and Z.<ref name="Raja_lambda" />