RNA splicing and processing are essential steps in the maturation of precursor messenger RNA pre-mRNA into mature mRNA, which is then translated into proteins. These processes involve a series of chemical mechanisms that determine gene expression and protein production.1. RNA splicing: This process removes introns non-coding regions from pre-mRNA and joins exons coding regions together to form a continuous coding sequence. The splicing process is carried out by a large ribonucleoprotein complex called the spliceosome, which consists of small nuclear ribonucleoproteins snRNPs and other associated proteins.The chemical mechanism of RNA splicing involves the following steps:a. Recognition of splice sites: The spliceosome recognizes the 5' and 3' splice sites at the exon-intron boundaries, as well as the branch point sequence within the intron.b. Formation of the lariat intermediate: The 2' hydroxyl group of the branch point adenosine attacks the 5' splice site, resulting in the cleavage of the 5' exon-intron junction and the formation of a lariat structure with the intron.c. Exon ligation: The 3' hydroxyl group of the 5' exon attacks the 3' splice site, resulting in the cleavage of the 3' exon-intron junction and the ligation of the two exons.d. Intron release: The intron lariat is debranched and degraded, and the spliced mRNA is released.2. RNA processing: In addition to splicing, pre-mRNA undergoes other processing events to become mature mRNA. These include:a. 5' capping: A 7-methylguanosine cap is added to the 5' end of the pre-mRNA. This cap protects the mRNA from degradation, promotes nuclear export, and aids in translation initiation.b. 3' polyadenylation: A poly A tail, consisting of multiple adenosine residues, is added to the 3' end of the pre-mRNA. This tail protects the mRNA from degradation, aids in nuclear export, and enhances translation efficiency.c. RNA editing: In some cases, specific nucleotides within the pre-mRNA are modified, such as deamination of adenosine to inosine or cytidine to uridine. This can alter the coding sequence and result in the production of different protein isoforms.These RNA splicing and processing events are crucial for determining gene expression and protein production. They ensure that the mature mRNA contains the correct coding sequence and is properly modified for stability, nuclear export, and efficient translation. Additionally, alternative splicing can generate multiple mRNA isoforms from a single gene, increasing the diversity of proteins that can be produced.