Editing Lambda phage (section)

===== Leftward Transcription mutations =====
Leftward transcription is believed to result in a deletion mutation of the ''rap'' gene resulting in a lack of growth of lambda phage. This is due to RNA polymerase attaching to pL promoter site instead of the pR promotor site. Leftward transcription results in ''bar''I and ''bar''II transcription on the left operon. Bar  positive phenotype is present when the ''rap'' gene is absent. The lack of growth of lambda phage is believed to occur due to a temperature sensitivity resulting in inhibition of growth.<ref>{{cite journal | vauthors = Guzmán P, Guarneros G | title = Phage genetic sites involved in lambda growth inhibition by the Escherichia coli rap mutant | journal = Genetics | volume = 121 | issue = 3 | pages = 401–409 | date = March 1989 | pmid = 2523838 | pmc = 1203628 | doi = 10.1093/genetics/121.3.401 }}</ref>