Answer:
- Duplex RNA (dsRNA) can suppress the expression of a gene.
- miRNAs are short, single strands approximately 21 nucleotides long.
- miRNAs suppress gene expression by interfering with transcription.
- RNA interference can temporarily suppress the expression of a target gene.
Explanation:
The RNA interference (RNAi) mechanism is a naturally occurring biological process by which an organism suppresses gene expression by using sequence-specific small non-coding RNAs that are complementary to RNA (posttranscriptional silencing) or DNA (transcriptional silencing) sequences. Since its discovery, this mechanism has been exploited in molecular biology to control the expression of target genes. There are different classes of non-coding RNAs which are able to trigger RNAi gene silencing: microRNAs (miRNAs), small interfering RNAs (siRNAs), piwi-interacting RNAs (piRNAs, only present in animals), etc. During their functioning, these non-coding RNAs are loaded into the RNA-induced silencing complex (RISC) to direct them to target sequences and trigger RNAi (for example, by cleaving target mRNAs). miRNAs are short, evolutionary conserved RNAs, that associate to the RISC complex in order to trigger both transcriptional and posttranscriptional gene silencing. During their biogenesis, small non-coding RNAs are double-stranded RNA (dsRNA), but they lose a strand (the passenger strand) when associate with the RISC complex, conserving only one strand (the guide strand) that bind by complementary base pairing to target sequences (either DNA in the nucleus or RNA in the cytoplasm).
