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Name: Elpasado
Status: student
Grade: n/a
Location: Outside U.S.
Country: Serbia
Date: Winter 2013-14


Question: How ribosomes know what is intron and what is exon ? And are there specific nucleotide order that is typical for each of these?



Replies:
Hi Elpasado,

It's been discovered with several ribosomes, the exact locations were identified by noting similarites in the sequences and ending nucleotide at the intron/exon and exon/intron junctions.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC319133/

"...certain characteristics exist near the ends of these introns. (i) An exon ends in T at the exon/intron junction and an intron ends in G at the intron/exon junction in all cases. (ii) For each intron, direct repeats several nucleotides long are present 5 to approximately 30 nucleotides upstream from both the exon/intron and intron/exon junctions."

Hope this helps. -Alex Viray


Cutting out of introns happens in the nucleus. The ribosomes are located in the cytoplasm. Only the exons remain once the mRNA leaves the nucleus.

vanhoeck



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