The other object is a small charged sphere that is free to move (we neglect the force of. gravity on this sphere). According to Coulombâs law, these two like charges repel each. another. That is, the small sphere experiences a repulsive force away from the van de. Graaff sphere. Figure 2.2.2 (a) Two charges of the same sign that repel one another because of the. âstressesâ transmitted by electric fields.
Transcription is the first step of gene expression, in which a particular segment of DNA is copied into RNA (mRNA) by the enzyme RNA polymerase.
Transcription is carried out by an enzyme called RNA polymerase and a number of accessory proteins called transcription factors. Transcription factors can bind to specific DNA sequences called enhancer and promoter sequences in order to recruit RNA polymerase to an appropriate transcription site.Together, the transcription factors and RNA polymerase form a complex called the transcription initiation complex.his complex initiates transcription, and the RNA polymerase begins mRNA synthesis by matching complementary bases to the original DNA strand. The mRNA molecule is elongated and, once the strand is completely synthesized, transcription is terminated.