Editing Lambda phage (section)

====Rightward transcription====
Rightward transcription expresses the ''O'', ''P'' and ''Q'' genes. O and P are responsible for initiating replication, and Q is another antiterminator that allows the expression of head, tail, and lysis genes from ''P<sub>R’</sub>''.<ref name="src3"/>

Pr is the promoter for rightward transcription, and the cro gene is a regulator gene. The cro gene will encode for the Cro protein that will then repress Prm promoter.  Once Pr transcription is underway the Q gene will then be transcribed at the far end of the operon for rightward transcription. The Q gene is a regulator gene found on this operon, which will control the expression of later genes for rightward transcription. Once the gene's regulatory proteins allow for expression, the Q protein will then act as an anti-terminator. This will then allow for the rest of the operon to be read through until it reaches the transcription terminator. Thus allowing expression of later genes in the operon, and leading to the expression of the lytic cycle.<ref>{{cite journal | vauthors = Thomason LC, Schiltz CJ, Court C, Hosford CJ, Adams MC, Chappie JS, Court DL | title = Bacteriophage λ RexA and RexB functions assist the transition from lysogeny to lytic growth | journal = Molecular Microbiology | volume = 116 | issue = 4 | pages = 1044–1063 | date = October 2021 | pmid = 34379857 | pmc = 8541928 | doi = 10.1111/mmi.14792 }}</ref>

Pr promoter has been found to activate the origin in the use of rightward transcription, but the whole picture of this is still somewhat misunderstood. Given there are some caveats to this, for instance this process is different for other phages such as N15 phage, which may encode for DNA polymerase. Another example is the P22 phage may replace the p gene, which encodes for an essential replication protein for something that is capable of encoding for a DnaB helices.<ref name="src3"/>