Recent observations indicate that alternative splicing is a common way for eukar
ID: 67546 • Letter: R
Question
Recent observations indicate that alternative splicing is a common way for eukaryotes to expand their repertoire of gene functions. Studies indicate that approximately 50 percent of human genes exhibit alternative splicing and approximately 15 percent of disease-causing mutations involve aberrant alternative splicing. Different tissues show remarkably different frequencies of alternative splicing, with the brain accounting for approximately 18 percent of such events.
(a) Define alternative splicing and speculate on the evolutionary strategy alternative splicing offers to organisms.
(b) Why might some tissues engage in more alternative splicing than others?
Explanation / Answer
(a). The DNA of eukaryotes contains “introns,” which protect the gene from damage. During transcription, these introns also get transcribed, and the pre mRNA contains introns. These introns are cut to form the mature mRNA, and the “exons” are spliced together. If the introns are not cut, the mRNA may code for non-functional proteins.
Alternative splicing, i.e. removal of different portions of genes of introns (so, a gene is intron sometime, and exon sometime) help in the synthesis of various proteins from the same mRNA. Thus, RNA splicing does not always results in the removal of same introns, which is an advantagious evolutionary strategy offered to organisms (they can make many new proteins).
(b) Some tissues engage in more alternative splicing than others because they are more engaged with multitasking, so they use more proteins (Eg: brain tissue).
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