Final answer:
The extent of complementarity of a miRNA with its target mRNA determines whether the mRNA is degraded or translation is inhibited. MiRNAs are key post-transcriptional regulators with implications for diseases such as cancer, and they function through their integration with the RISC complex.
Step-by-step explanation:
The extent of complementarity of a miRNA with its target mRNA determines the fate of the mRNA molecule, which can involve degradation or inhibition of translation. MicroRNAs (miRNAs) are short RNA molecules averaging around 21-23 nucleotides in length that regulate gene expression at the post-transcriptional level. Various processes, such as RNA interference and gene silencing, utilize miRNAs to target and pair with complementary sequences on mRNA. If a miRNA is fully complementary to its target mRNA, it can lead to mRNA degradation. This mechanism plays a significant role in biological pathways and has crucial implications in medical conditions, including cancer, where altered miRNA expression is associated with disease states.
MicroRNAs associate with the RNA-induced silencing complex (RISC) after being processed by enzymes like Drosha and Dicer from their precursor forms. Upon binding to RISC, miRNAs guide the complex to their complementary mRNA targets. The high specificity and diverse target range of miRNAs make them promising candidates for cancer therapeutics, by either upregulating or downregulating their expression or function to address aberrant gene expression characteristic of cancer.