Question

What happens to RNA polymerase II after it has completed transcription of a gene? a. It begins transcribing the next gene on the chromosome. b. It is free to bind to another promoter and begin transcription. c. It is degraded. d. It joins with another RNA polymerase to carry out transcription.

Answer 1

The correct answer is: b. It is free to bind to another promoter and begin transcription

Transcription is the first step of gene expression in which DNA molecule is copied (transcribed) into RNA (mRNA) by RNA polymerase. The process of transcription is divided into three phases:

1. Initiation

• RNA polymerase with transcriptional factors bind to gene promoter  

• RNA polymerase unwinds DNA double helix (transcription bubble is formed)

2. Elongation

• RNA polymerases adds nucleotides complementary to DNA  

3. Termination

• RNA polymerase gets to stop codon (transcribes a sequence of DNA known as a terminator)

• Formed complementary RNA strand is released from DNA-RNA complex.

RNA polymerase is also released and can transcribe some other gene by binding to its promotor. RNA polymerase will transcribe just the genes whose products are needed at a particular moment.