| Popis: |
One of the most important and exciting unsolved problems in molecular biology is concerned with the differential expression of the genetic information in eukaryotic organisms. Although the issue is by no means clearly resolved it is generally assumed that the heart of this problem lies at the level of transcriptional control rather than at the later stages of translation or post-translation, and it is at the genetic material itself, the chromatin, that attention has been primarily focused for clues to the nature of the control process. Transcription of m-RNA occurs in three stages: initiation which is the binding of RNA polymerase to a specific recognition site in the DNA; elongation which is the sequential production of m-RNA on one stand of the DNA template; termination, which is the release of the completed m-RNA and also, presumably, the RNA polymerase. Control of the rate of transcription may operate at any or all of these stages. |
