Which of the following statements are correct with reference to a transcription unit? A. A transcription unit in DNA is defined primarily by three regions : promoter, structural gene and terminator. B. The promoter is said to be located towards the 5-end of the structural gene. C. The promoter is a DNA sequence that provides binding site for RNA polymerase. D. The promoter defines the template and coding strands. E. The terminator is located towards the 3-end of the coding strand and it defines the end of the process of transcription. Choose the correct answer from the options given below:

Solution & Explanation

Answer: (D) A, B, C, D and E. All five statements are correct: a transcription unit has three regions (promoter, structural gene, terminator); the promoter lies towards the 5'-end of the structural gene, provides the RNA polymerase binding site, and its presence defines the template and coding strands; the terminator lies towards the 3'-end of the coding strand and ends transcription. NCERT Ch 5, p.92, lines 019-026: "The promoter is said to be located towards 5'-end (upstream) of the structural gene... It is a DNA sequence that provides binding site for RNA polymerase, and it is the presence of a promoter in a transcription unit that also defines the template and coding strands... The terminator is located towards 3'-end (downstream) of the coding strand and it usually defines the end of the process of transcription."