question_answer

Transcription is considered to be a more complex process in the eukaryotic cells. Explain.

Answer:

Transcription is considered to be a more complex process in eukaryotic cells because of the following features

(i) In nucleus, there are three types of RNA polymerases and there is division of labour.

(a) RNA polymerase - I, transcribes rRNAs.

(b) RNA polymerase - II, transcribes precursor mRNA, i.e. hnRNA.

(c) RNA polymerase - III, transcribes tRNA and other small RNAs.

(ii) hnRNA (primary transcript of mRNA) contains both coding sequences called exons and non - coding sequences called introns. So, it undergoes splicing, in which non - coding sequences (introns) are removed and the coding sequences (exons) are joined together in a defined order.

(iii) Eukaryotes require processing of mRNA to make it active.