Question

MicroRNA (miRNA) regulate the expression of eukaryotic genes by?

a.	promoting packing of chromatin into heterochromatin
	b.	suppressing the binding of general transcriptional factor to promoter
	c.	promoting mRNA degradation and inhibiting mRNA translation via binding to mRNA
	d.	inhibiting intron splicing by binding to spliceosome
	e.	suppressing mRNA transport from the nucleus to the cytoplasm

Answer 1

The correct option is c - promoting mRNA degradation and inhibiting mRNA translation via binding to mRNA

microRNA (miRNA) is a small, single-stranded, non-coding RNA molecule that mediates silencing of the RNA. In eukaryotes, miRNA regulates gene expression post-transcriptionally by inhibition and degradation. miRNA binds with target mRNA and chop the mRNA into two pieces. This results in the breaks down of the mRNA. microRNA also blocks translation. miRNA binds with 3'UTR (untranslated region) of the target mRNA and breaks down the poly-A tail. Thereby, miRNA promotes mRNA degradation and prevents the translation into protein and results in gene expression regression