polycistronic vs monocistronic

[m25]

---

Members do not see this ad.

How do polycistronic gene work as opposed to monocistronic gene? I know that polycistronic genes codes for more than 1 protein while monocistronic gene codes for only 1 protein, but what exactly does that mean?

So given that polycistronic and monocistronic gene both makes protein A, B, and C:
First, both genes get transcribed from DNA to mRNA, forming a single long strand, and polycistronic gets translated in the form of a single long strand of mRNA that gives rise to proteins A B C after translation, while monocistronic mRNA gets spliced after post-transcriptional processing, forming 3 separate mRNA strands that separately codes for protein A, B, and C?

Also, is alternative splicing always associated with monocistronic gene since it is part of post-transcriptional processing, which only happens in monocistronic gene ?

 

[Czarcasm]

Polycistronic (poly meaning "many"; cistron meaning "genes"); applies to Prokaryotic species. A good example is the regulate gene in E. Coli, the Lac Operon, which among other features contains a structural gene region that encodes multiple protein products responsible for lactose metabolism. This genetic feature, where families of interrelated genes are transcribed as a series into one single strand of mRNA, occurs frequently in prokaryotic species. Upon translation, which generally occurs as transcription is still occuring, all these proteins are translated collectively from the same mRNA strand.

Monocistronic (mono meaning "one"; cistron meaning "gene"); applies to Eukaryotic species . Once our mRNA is processed (spliced: regardless if we're referring to constitutive or alternative splicing), that mRNA gives rises to a single protein upon translation.

I think the best way to really understand the difference is through a picture, so take a good look at this url:

http://4.bp.blogspot.com/-RP314Y5rG6Q/UFkyeB726ZI/AAAAAAAADE0/fPHjkm0Dkfg/s1600/prokaryotic vs eukaryotic mrna.jpg

 

[Cawolf]

Haha the good old lac operon. . ..