Describe three molecular changes that take place during the processing of eukaryotic mRNA?
Asked By Zai Lee
Replied by Admin
Three ways that eukaryotic mRNAs processed in the nucleus before they are translated in the cytosol are : RNA processing means precursor mRNA undergoes maturation into functional tRNAs, rRNAs, and mRNAs. It occurs after the transcription and before to translation into a protein.
1) 5? capping
2) RNA splicing
3) 3? polyadenylation
1) Capping at the 5'- End : 7- methyl guanosine is added at the 5’ end of eukaryotic RNAs by a 5’-5’ triphosphate linkage. It occurs in nuclei before splicing. This 5’cap protects the RNA from ribonucleases.
2) Poly-A Tail at 3' -END : Eukaryotic RNAs has 80 to 250 A residues at the 3’ end and that poly A tail protects mRNA from enzymatic destruction and acts as binding site for proteins. This tailing process occurs in the nuclei before splicing.
3) mRNA Splicing : mRNA splicing is the process through which introns, which are called as non-coding are removed from RNA transcripts and coding exon is translated into amino acids.
RNA transcript can be spliced by more than one pathway that depends on the type of intron and it spliced out of the mRNA. One common pathway is through spliceosome. Self-splicing mRNA does not require spliceosome to remove the intron from the mRNA. Alternative splicing is the process in which exons are removed or joined in various combinations that results in multiple protein isoforms and are encoded by a single gene.
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- 18 Dec 2018 @ 10:25