Question

When Rho catches up with RNA polymerase it _______

(a) Stalls

(b) Falls off

(c) Backtracks

(d) Moves on

The question was asked during a job interview.

My doubt stems from Transcription in Prokaryotes : Termination in section Gene Expression : Transcription Prokaryotes of Cytogenetics

Answer 1

Right option is (b) Falls off

To explain I would say: Rho protein helps in termination of transcription. It binds to the growing transcript rolls up and catches up with the polymerase when the loop starts to form. This dissociates the complex from the DNA leading to the formation of free Rho, DNA, RNA transcript and polymerase.