Immediate Early and Delayed Early Genes:
Immediate Early and Delayed Early Genes: Lambda immediate early and delayed early genes needed for both lysogeny and the lytic cycle.
Immediate genes transcribed by host RNA polymerase: • Cro – repressor that prevents expression of cI gene. • N – antitermination factor, acts at nut sites allowing transcription through delayed early genes. After first only N and cro made (due to terminators tL and tR), pN allows RNA polymerase to synthesise more genes. Three of the delayed early genes are regulators: cII, cIII, and Q. Lysogeny requires the delayed early genes cII-cIII (synthesis of lambda repressor). The lytic cycle requires the immediate early gene cro and the delayed early gene Q (antiterminator). PL /OL = left promoter/operator. PR /OR= right promoter/operator. Lie either side of cI gene.
Immediate genes transcribed by host RNA polymerase: • Cro – repressor that prevents expression of cI gene. • N – antitermination factor, acts at nut sites allowing transcription through delayed early genes. After first only N and cro made (due to terminators tL and tR), pN allows RNA polymerase to synthesise more genes. Three of the delayed early genes are regulators: cII, cIII, and Q. Lysogeny requires the delayed early genes cII-cIII (synthesis of lambda repressor). The lytic cycle requires the immediate early gene cro and the delayed early gene Q (antiterminator). PL /OL = left promoter/operator. PR /OR= right promoter/operator. Lie either side of cI gene.
