Practice question

RNA editing encompasses post-transcriptional processes altering nucleotide sequence of primary transcript after synthesis, thereby changing coding potential without modifying genome. Mechanisms include site-specific insertion or deletion of nucleotides, such as uridine insertion guided by guide RNAs in trypanosome mitochondria creating correct reading frames, and deaminase-mediated base conversions C-to-U in apolipoprotein B mRNA or A-to-I in neuronal receptors catalyzed by ADAR enzymes converting codon and affecting splicing patterns. Editing can affect stability, localization, and translation efficiency and contributes to transcriptome diversification beyond genomic information.