Question

name TWO mechanisms of control of gene expression that are only used by eukaryotes and EXPLAIN WHY each of those mechanisms wouldn’t be possible in prokaryotes.

Answer 1

There are four levels of regulation of gene expression in eukaryotes -

Transcriptional control

Control during RNA processing

Control during RNA transport

Translational control

Out of these four levels, transcriptional control and translational control are common to prokaryotes and eukaryotes. This is because transcription and translation occur in both of them.

But control during RNA processing and RNA transport is exclusive to eukaryotes only. RNA processing is the method by which introns are removed and exons are joined together. Introns are absent in prokaryotes and therefore RNA processing does not occur. Hence control of gene expression at the level of RNA processing does not occur in prokaryotes.

On the other hand, control during RNA transport occurs in eukaryotes when RNA is being transported from nucleus into cytoplasm. RNA is synthesized in nucleus but it undergoes translation in cytoplasm so it is to be transported. But nucleus is absent in prokaryotes. Translation and transcription takes place in cytoplasm only. So there is no RNA transport in prokaryotes and hence no control of gene expression at this level.

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