What are the differences between siRNA and MiRNA ?

Basis of differentiation

siRNA

miRNA

Expression

Inhibits the expression of one specific target mRNA

Regulates the expression of multiple mRNAs

Number of DNA strands

SiRNA is considered external double-stranded RNA

miRNA is single-stranded 

Nature of RNA

Exogenous

Endogenous

Pairing

Is an ideal pairing, since it is specific to one mRNA target

Its imperfect pairing can inhibit the translation of various mRNA targets

Structure

These RNA duplexes are 21-23 nucleotides in length and have a two-nucleotide overhang at the 3' end.

These are RNA molecules that are 19-25 nucleotides long and form hairpin structures when they pair with each other

Occurrence

Found in lower animals and plants, but absent in mammals.

Observed in all plants and animals

Gene silencing requirement

Ago2 protein (also known as argonaute protein 2) is necessary.

Any protein within the argonaute family, not specifically Ago2, can be involved in gene silencing regulated by miRNA

Regulatory structures

Controls the expression of different genes

Controls the expression of genes that share similarities or have a common origin.