Devoting a few sentences to each, describe the following structures or complexes and their effects on eukaryotic gene expression: RISC

Key Concepts

RNA-Induced Silencing Complex (RISC)

RISC is a multi-protein complex that plays a crucial role in RNA interference (RNAi), a biological process that regulates gene expression. It incorporates small RNA molecules, such as microRNAs (miRNAs) or small interfering RNAs (siRNAs), which guide the complex to complementary mRNA targets. Once bound, RISC can either degrade the mRNA or inhibit its translation, effectively silencing the gene associated with that mRNA.

MicroRNAs (miRNAs)

MicroRNAs are short, non-coding RNA molecules that regulate gene expression by binding to complementary sequences in target mRNAs. They are processed from longer precursor molecules and play a significant role in post-transcriptional regulation. By influencing the stability and translation of mRNAs, miRNAs can modulate various biological processes, including development, differentiation, and response to stress.

Gene Silencing

Gene silencing refers to the process by which the expression of a gene is inhibited or completely turned off. This can occur through various mechanisms, including RNA interference, where RISC and small RNAs target specific mRNAs for degradation or translational repression. Gene silencing is essential for regulating gene expression in response to environmental changes and is also a key mechanism in developmental processes and cellular differentiation.