12th Class Biology Molecular basis of inheritance

  • question_answer 38)   The RNA polymerase holoenzyme transcribes (a) the promoter, structural gene and the terminator region (b) the promoter and the terminator region (c) the structural gene and the terminator regions (d) the structural gene only


                      (c) In E. coil (bacterium, the RNA polymerase has co-factors p, [3', a, a' and co along with(sigma) factor, to catalyze the process. The transcription is completed in three steps. Initiation o (sigma) factor recognizes the start signal and promoter region on DNA which then along with RNA polymerase binds to the promoter to initiate transcription.     Elongation The RNA polymerase after initiation of RNA transcription loses the  factor but continues the polymerization of rib nucleotides to form RNA, Termination Once the RNA polymerase reaches the termination region of DNA, the RNA polymerase is separated from DNA-RNA hybrid, as a result nascent RNA separates. This process is called termination which is facilitated by a termination factor(rho).                                                                             In prokaryotes, mRNA does not require any processing, so both transcription and translation occur in the cytosol. It can be said that transcription and translation are coupled together.

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