Suppose you want to study the transcription in vitro of one particular gene in a dna molecule that contains several genes and promoters. part awithout adding specific regulatory proteins, how might you stimulate transcription from the gene of interest relative to the transcription of the other genes on your dna template?

In order to make all the complexes identical, one would like to arrest all the transcriptional events at the similar position on the template of the DNA prior of isolating the complex. To arrest the transcription events at the similar positions, a dinucleotide that is complementary to the initial two nucleotides can be incorporated.

This will not permit the inclusion of the initial nucleotide. Thus, one can get the similar nucleotides each of the similar length that has been arrested at a similar position. This can be arrested by supplementing only two or three in spite of for ribonucleotide triphosphates at the location where the transcription has been arrested.