(58)
8. Beskrive monocystron (eukaryout) og polycystron (prokaryot) mRNA
Devlin, s.235

I am also going to describe the general differences between eukaryotic and prokaryotic mRNA.  

Eukaryotic mRNA has the following characteristics:

• it is monocistronic – one mRNA molecule encodes a single polypeptide

• has a cap of 7-methylguanosine at the 5’ end

• has a 5’ non-translated region, which can be short or up to a few hundred nucleotides

• has a translation initiation signal, which is very often the first encountered AUG sequence when the mRNA is read in the 5’-3’ direction

• has a translation termination signal

• has a 3’ non-translated sequence, usually up to 100 nucleotides

• has a poly (A) tail of up to 250 A-residues

Prokaryotic mRNA:

• most mRNA is polycistronic, meaning it encodes for two or more polypeptide chains, and it also includes two or more AUG initiation sequences. The first AUG sequence is found about 25 nucleotides from the 5’-end of the mRNA

• a ribosome positioning sequence, called Shine-Delgarno sequence, is found 10 nucleotides upstream from the AUG initiation sequence

• it has a 3’ non-translated sequence

• no cap, no poly (A)-tail

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