R rna processing
- 1. r RNA Processing Presented by Banupriya
- 2. Introduction Ribosome consist of r RNA (65%) and protein(35%) Ribosomal RNA (rRNA) :Along with numerous proteins, helps form the large and small ribosomal subunits that unite for translation of mRNA rRNAs are transcribed as large precursor molecules that are cleaved into smaller RNA molecules by removal and discarding of spacer sequences intervening between the sequences of the different RNAs. The four rRNAs in eukaryotes are first transcribed as two long precursor molecules. One contains just the pre- rRNA that will be processed into the 5S rRNA; the other spans the 28S, 5.8S, and 18 S rRNAs.
- 5. What is r RNA processing ? It is the process of modification, mainly through cleavage & or splicing, of primary RNA transcripts so as to release functional RNA molecules from them.It is carried out by ribonucleases (RNases) that cleave RNA.
- 6. How actual r RNA processing takes place ? Processing of 45s molecules occurs inside nucleolus. 45s molecules tightly associated protein forming ribosome (RNPS) First cleavage: occurs at site I & remove 5' terminal leader sequence, produces 41s intermediate & 18s. Second cleavage: occurs 41s intermediate at site 3'generates 32s intermediate. Final cleavage: separation of 32s intermediate into 28. 5.8s Processed rRNA 28s. 5.8s & 18s
- 8. Mature rRNAs make up 50-60% of each ribosome.
- 9. Thank You!!!