Figure 27-2: The bacteriophage lambda chromosome. Features of the bacteriophage lambda chromosome are shown in a diagrammatic and somewhat simplified form. Genes are represented by rectangles (white, transcribed rightward; gray, transcribed leftward; vertical positions are varied for graphical clarity). Selected gene names are given on or above these rectangles. Asterisks (*) denote genes that are expressed in the lysogen and diamonds denote regulatory genes. A scale in kilobasepairs is shown below the genes, and below this the major characterized transcripts are indicated by black arrows. Important promoters are indicated by small arrows, and other important DNA sites are marked by vertical lines, just above the kbp scale. The slanted arrow between the G and T reading frames indicates a programmed translational frameshift (see text). The region names b2, Ea, PPEL (promoter proximal early left), nin, PPL (promoter proximal late) and ERE (extreme right end) are discussed in the text.