Question

Compare and contrast transcription termination in bacteria and eukaryotes. a) What sites signal the transcription complex to terminate in prokaryotes and to terminate/polyadenylate in eukaryotes

Answer 1

Answer:

Prokaryotes have RHO dependent and RHO independent transcription termination; Eukaryotes have the poly A signal and downstream termination sequence transcription termination.

Explanation:

Transcription is the process by which mRNA is synthesized from DNA by the enzyme RNA polymerase. The process of transcription is keep going until some termination signal/mechanism stops it. There are various differences of transcription in prokaryotes and eukaryotes like types of RNA polymerases, nitrogenous bases utilized and the mechanism of transcription termination.

Prokaryotic termination may be dependent on RHO proteins or not.

• In RHO dependent pathway the RHO factor (protein) slide towards the RNA polymerase along the DNA and dissociate it from DNA.
• In RHO independent pathway a stem loop is formed by mRNA from a sequence which pasues the polymerase temporarily and consequently causes dissociation of RNA polymerase with help of poly-uracil sequence.

Eukaryotic termination may occur through poly A signal and downstream termination sequence;

• Poly A tail is added  mRNA for its protection. It prevent the mRNA degradation.
• The polymerases pauses on the termination signal and ultimately dissociates from DNA.