Final answer:
This question focuses on microRNAs (miRNAs), which regulate about one-third of human protein-coding genes by degrading or inhibiting messenger RNAs. The recent discoveries about smORFs add complexity to the regulation of gene expression.
Step-by-step explanation:
The subject of this question is the role of microRNAs (miRNAs) in the regulation of gene expression in humans. miRNAs are a group of small, non-coding RNA molecules that consist of approximately 21-24 nucleotides. They are initially transcribed as longer precursors and are subsequently processed by an enzyme called Dicer to form mature miRNAs. Once mature, they associate with a ribonucleoprotein complex known as the RNA-induced silencing complex (RISC), which can bind to messenger RNAs (mRNAs) to degrade them or inhibit their translation. This complex regulation of gene expression by miRNAs has significant implications for cellular functions and diseases. It is estimated that miRNAs can regulate about one-third of all protein-coding genes in humans, highlighting their critical role in post-transcriptional control of gene expression.
Furthermore, the discovery of other small open reading frames (smORFs) within long non-coding RNAs (IncRNAs) suggests that the human genome may encode for more proteins than previously thought. These smORFs are translated into short peptides, adding another layer to the complex gene regulation mechanisms in human cells.