Table of contentsProcessing of rRNA and tRNA:MRNA processing in eukaryotesReferences:Functional RNAs are produced by modification of the pre-RNA produced from the transcription process, with the exception of bacterial mRNAs which as such are used for protein synthesis without any modification. These series of changes involving the removal of introns through splicing are known as RNA processing. Say no to plagiarism. Get a tailor-made essay on “Why Violent Video Games Should Not Be Banned”? Get the original essay Processing of rRNA and tRNA: The processing of rRNA and tRNA in prokaryotes and eukaryotes is similar. Eukaryotes – 4 species of rRNA, three of which (28S, 18S and 5.8S) are derived by cleavage of a single long precursor transcript (pre-rRNA). While the fourth (5S) is transcribed from a separate gene. There are 3 rRNAs in prokaryotes (23S, 16S and 5S) which are also transcribed from a single pre-rRNA transcript. In prokaryotic cells, initial cleavage results in a separate precursor of 3 individual rRNAs which undergo secondary cleavage to produce functional forms. Whereas in eukaryotic cells (within the nucleolus), the initial cleavage near the 5' side of the 5.8S rRNA gives rise to 2 segments (18S and 28S + 5.8S). Further cleavage produces functional forms with 5.8S having a hydrogen bond to 28S. Apart from this, there will also be an addition of methyl groups to the bases and sugar moieties of specific nucleotides and a conversion of some uridines to pseudouridines. Similarly, from pre-tRNAs, individual tRNAs are synthesized in prokaryotes and eukaryotes. In prokaryotes, some tRNAs are included in pre-tRNA transcripts. RNase P enzyme (ribozyme) involved in processing at the 5' end of pre-tRNAs. It consists of RNA molecules and proteins. Here, RNA is responsible for catalytic activity while proteins are required for maximum activity. Processing of the 3' end involves the action of conventional RNase protein and the addition of a CCA end. As these CCA sequences are the protein attachment site, they are present in all tRNAs for protein synthesis. Additionally, approximately 10% of specific nucleotide bases are modified. Introns are spliced ​​using endonucleases from pre-tRNAs. mRNA processing in eukaryotesUnlike prokaryotes, pre-mRNAs synthesized in the nucleus of eukaryotes are modified before being transported to the cytoplasm. Processing involves editing both ends of the original transcript and removing introns. The C-terminal domain (CTD) of RNA polymerase II serves as a binding site for enzyme complexes. While polymerases I and III lack CTDs, their transcripts are therefore not processed by the same enzymatic complexes. 5' end treatment – ​​addition of 7-methylguanosine cap. After transcription of the first 20 to 30 nucleotides, capping enzymes are recruited to the pCTD. Capping initiated by the addition of a GTP in reverse orientation to the 5' terminal nucleotide. Followed by the addition of a methyl group to this G residue and to the ribose fragments of one or two nucleotides 5'. This 5' cap helps stabilize and align ribosomes during protein synthesis. At the 3' end – cleavage of the primary transcript downstream up to 10-30 nucleotides of highly conserved hexanucleotide (AAUAAA in mammalian cells) and addition of a poly-A tail known as polyadenylation. Thus, residues rich in GU are degraded. Keep in mind: this is just a sample. Get a personalized item now from.