Question

E: For each of the following, indicate whether they regulate eukaryotic gene expression at the transcription level (prior to or during transcription), at the translation level (after transcription/formation of the immature mRNA molecule), or both. 1. Alternative splicing 2. Chromatin remodeling 3. RNAi 12pt v Paragraph Β Ι Ο Α ev T²w ...

Answer 1

Alternative splicing occurs after formation of immature RNA post-transcriptionally. Immature RNA contains exons and introns in alternative arrangement. Exons code for protein but introns don't code for protein. During splicing intronic sequences are removed from immature RNA. Removal of intronic sequences generate mature RNA, which enters into translation. During alternative splicing, some of the exons may also be skipped generating different mature mRNAs ( varies in sequence composition). Thus, alternative splicing helps to generate different mature mRNAs from the same immature mRNA. Thus, this is one the main forms of regulations in gene expression.

Chromatin remodeling occurs during before and during transcription initiation. Different chromatin remodeling complexes along with histone codes regulates gene expressions.

RNAi or RNA interference occurs post-transcriptionally. mi-RNA (micro RNA) controls gene expression by binding to the 3' UTR ( untranslated region) of the matured mRNAs and mediates degradation of mRNAs. Thus, even if transcription occurs, translation of that particular gene is halted.