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When [[MRNA|mRNA]] is produced from [[Eukaryotic|eukaryotic]] [[DNA|DNA]] by [[RNA polymerase|RNA polymerase]], primarily the [[DNA|DNA]] transcribed creates [[pre-mRNA|pre-mRNA]] which includes both [[Introns|introns]] and exons.  
When the transcription of [[Eukaryotic|eukaryotic]] [[DNA|DNA]] by [[RNA polymerase|RNA polymerase]] occurs, the [[DNA|DNA]] transcribed produces [[Pre-mRNA|pre-mRNA]] which includes both [[Introns|introns]] and exons.  


[[Introns|Introns]] are non-coding elements of DNA (however, often have a regulatory function). Exons are the [[Protein|protein]] coding regions of [[DNA|DNA]].   
[[Introns|Introns]] are non-coding elements of DNA (however, often have a regulatory function). Exons are the [[Protein|protein]] coding regions of [[DNA|DNA]].   


Pre-mRNA is processed into mature [[MRNA|mRNA]] - the [[Introns|introns]] are removed, the exons are spliced together and a [[Poly-A tail|poly-A tail]] is added.<br>The mature [[MRNA|mRNA]] is then suitable for [[Translation|translation]].  
Pre-mRNA is processed into mature [[MRNA|mRNA]]&nbsp;by the removal and splicing of&nbsp;[[Introns|introns]]&nbsp;followed by the addition of a&nbsp;[[Poly-A tail|poly-A tail]]. &nbsp;The mature [[MRNA|mRNA]] is then suitable for [[Translation|translation]]&nbsp;into the coded proteins.&nbsp;


[[Prokaryotes|Prokaryotic]] [[DNA|DNA]] only have exons. [[Eukaryotic|Eukaryotic]] [[DNA|DNA]] include [[Introns|introns]] and exons.
[[Prokaryotes|Prokaryotic]] [[DNA|DNA]] only contain exons, whereas&nbsp;[[Eukaryotic|Eukaryotic]] [[DNA|DNA]] contain&nbsp;[[Introns|introns]] and exons.  
 
The average length of a exon is 145 base pairs<ref>Alberts B., Johnson A., Lewis J., Raff M., Roberts K., Walter P. (2008) Molecular Biology of the Cell, 5th edition, New York: Garland Science. Page 207.</ref>.<br>
 
=== References  ===
 
<references />

Latest revision as of 01:09, 22 October 2013

When the transcription of eukaryotic DNA by RNA polymerase occurs, the DNA transcribed produces pre-mRNA which includes both introns and exons.

Introns are non-coding elements of DNA (however, often have a regulatory function). Exons are the protein coding regions of DNA

Pre-mRNA is processed into mature mRNA by the removal and splicing of introns followed by the addition of a poly-A tail.  The mature mRNA is then suitable for translation into the coded proteins. 

Prokaryotic DNA only contain exons, whereas Eukaryotic DNA contain introns and exons.

The average length of a exon is 145 base pairs[1].

References

  1. Alberts B., Johnson A., Lewis J., Raff M., Roberts K., Walter P. (2008) Molecular Biology of the Cell, 5th edition, New York: Garland Science. Page 207.