Question

Alternative RNA splicing is a method that apparently evolved for the production of many different polypeptides from the same pre-mRNA. Provide an example of alternative splicing. Make sure your answer is completely.

Please can you type the answer. I don't understand the writing hand. Sometime.

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Answer 1

Maturation of eukaryotic mRNA usually involves the removal of RNA sequences (introns or intervening sequences), which do not code for protein from the primary transcript. The remaining coding sequences, the exons, are joined together to form mature mRNA. The process of removing introns and joining exons is called splicing. The molecular complex that accomplishes these task is known as spliceosome. The given figure shows the process of splicing.

Alternative mRNA splicing results from tissue - specific adaptive and development control mechanisms. This produces multiple variations of mRNA and, therefore, of its protein product. This appears to be a mechanism for producing a diverse set of proteins from a limited set of genes.

As shown in the given figure, the sequence of exon- intron splicing events follows a hierarchial order for a given gene. The fact that very complex RNA structures are formed during splicing and that a number of snRNAs and proteins are involved , affords numerous possibilities for a change of this order and for generation of different mRNAs. Similarly , the use of alternative termination - cleavage polyadenylation sites also results in mRNA variability.

Example of alternative mRNA splicing :- In eukaryotic cells the mRNA for tropomyosin , an actin filament - binding protein of the cytoskeleton and of contractile apparatus in muscle cells, undergoes extensive tissue specific alternative splicing with production of multiple isoforms of tropomyosin protein.