Question

Which of the following is a correct statement about rho independent termination?

1) It occurs when the RNA polymerase reaches a termination sequence and stops transcription.
2) It occurs when the RNA polymerase pauses at a termination sequence and then continues transcription.
3) It occurs when the RNA polymerase dissociates from the DNA template and stops transcription.
4) It occurs when the RNA polymerase adds a poly-A tail to the mRNA and stops transcription.

Answer 1

Rho-independent termination is a mechanism of terminating transcription in bacteria. The RNA polymerase encounters a region rich in C-G nucleotides, causing the mRNA to form a stable hairpin loop and the polymerase to stall. This leads to the dissociation of the RNA polymerase from the DNA template and the termination of transcription.

Step-by-step explanation:

Rho-independent termination is a mechanism of terminating transcription in bacteria. As the RNA polymerase nears the end of the gene being transcribed, it encounters a region rich in C-G nucleotides on the DNA template. The mRNA then folds back on itself, forming a stable hairpin loop, causing the polymerase to stall. The stalled polymerase, coupled with the weak interaction between the U-A region of the mRNA transcript and the template DNA, induces enough instability for the RNA polymerase to dissociate from the DNA template and stop transcription.