Final answer:
RNA interference (RNAi) is a post-transcriptional gene regulation process where RNA molecules like miRNA and siRNA target mRNA to control protein synthesis.
Step-by-step explanation:
A type of post-transcriptional gene regulation in which small RNA molecules interfere with gene expression is known as RNA interference (RNAi). This biological process occurs after the RNA molecule has been created but before it is translated into protein. It involves a variety of RNA molecules, such as microRNA (miRNA) and small interfering RNA (siRNA), which can target specific mRNA transcripts for degradation or prevent their translation, thereby regulating the level of proteins synthesized within the cell. These processes are crucial for the proper function of cells and have various applications in both research and medicine.