Transcription RNA is produced by transcription from the DNA template by RNA polymerase initiation - requires a promoter sequence in the DNA that the polymerase binds to, but no primer (unlike DNA polymerase) elongation - polymerizes ATP, GTP, CTP and UTP into a polynucleotide using only one strand of the DNA as a template (asymmetric transcription) synthesis is 5' to 3', going 3' to 5' on the DNA template strand (antiparallel just like the DNA polymerase) termination - specific DNA sequences called terminators signal the end of the transcript Try these questions about transcription: question1 question2 question3 from the Biology Project Two types of RNA produced by transcription unstable mRNA that is a carrier of genetic information and codes for proteins stable RNA that has a specific function of its own rRNA and tRNA - protein synthesis snRNA - splicing telomerase RNA - telomere synthesis editing RNA's A gene codes for a functional RNA molecule Either a mRNA or an RNA with a direct function There are some difference's between prokaryotic and eukaryotic transcription Different promoter and termination sequences Eukaryotes have three specialized RNA polymerases instead of just one Eukaryotic mRNAs are heavily processed Eukaryotic mRNA is heavily processed, unlike prokaryotic mRNA the initial transcript is called hnRNA (heterogenous RNA) because of the large range of sizes. This hnRNA is found only in the nucleus the hnRNa has sequences removed from each end and then a 5' cap (7methyl guanasine added 5' to 5') and a poly A tail (a string of about 300 As added to the 3' end of the RNA) are added introns are then spliced out - various stretches of RNA sequence are cut out of the transcript and then the remaining exons are spliced back together, the introns are presumably degraded Here is a more complete description of the discovery of introns, from the "DNA from the Beginning" site The finished mRNA is exported to the cytoplasm This document is copyright of Jeff Bell Last Update: Thursday, March 29, 2001