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प्रश्न
Give an account of post transcriptional modifications of a eukaryotic mRNA.
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उत्तर
The primary transcripts (hn-RNA) contain both the exons and the introns and are non-functional. Hence, it is subjected to a process called splicing where the introns are removed and exons are joined in a defined order. Intron is the portion of gene which is transcribed but not translated. In prokaryotes, hnRNA is absent so splicing in not required. hnRNA undergoes additional processing called as capping and tailing. In capping an unusual nucleotide (methyl guanosine triphosphate) is added to the 5′-end of hnRNA. In tailing, adenylate residues (200 - 300) are added at 3′-end in a template-independent manner. It is the fully processed hnRNA, now called mRNA, that is transported out of the nucleus for translation.
Process of Transcription in Eukaryotes
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संबंधित प्रश्न
Differentiate between the following:
mRNA and tRNA
Explain the process of transcription in Eukaryotes.
Methyl guanosine triphosphate is added at 5' end of hn-RNA in a process of ______.
If the base sequence of a codon in mRNA is 5'-AUG-3', the sequence of tRNA pairing with it must be ______.
In eukaryotes, the process of processing of primary transcript involves ______.
On the ribosome, mRNA binds ______ and two sites in the ______ for subsequent amino acids to bind to be close enough to each other for the formation of a peptide bond.
The most abundant type of RNA in the cell is ______.
A ribozyme is an:
The exon part of mRNA has code for ______
What are the functions of poly-A “tail” in a mature on RNA?
Observe the segment of mRNA given below.
(a) Explain and illustrate the steps involved to make fully processed hnRNA?
(b) Gene encoding RNA Polymerase I and III have been affected by mutation in a cell. Explain its impact on the synthesis of a polypeptide, stating the reasons.
Given below are two statements:
Statement I: Transfer RNAs and ribosomal RNA do not interact with mRNA.
Statement II: RNA interference (RNAi) takes place in all eukaryotic organisms as a method of cellular defence.
In the light of the above statements, choose the most appropriate answer from the options given below:
What is the consensus sequence of the –10 region (Pribnow Box) in bacterial promoters?
In which direction does RNA polymerase move along the template strand during bacterial transcription elongation?
Which of the following are the substrates used during RNA elongation in bacterial transcription?
Which mechanism of transcription termination in bacteria does not require a protein factor?
At which step of bacterial transcription does the sigma (σ) factor dissociate from the RNA polymerase?
Between rho-independent and rho-dependent termination, which mechanism is also known as intrinsic termination?
