Post-transcriptional modification

Transcription, translation, and post-translation regulation happens in both prokaryotes and eukaryotes
- Most regulations in terms of prokaryotic gene expression occur at transcription.
- post-transcriptional modification of RNA is a method of gene expression and doesn't happen in prokaryotes.
the most significant d/f between eukaryotes and prokaryotes is:
- The absence of a nuclear membrane surrounding the genetic material in prokaryotes.
  - This means that transcription and translation can be coupled
- The presence of nuclear membrane surrounding the genetic material in eukaryotes
  - This separates the location of transcription and translation into d/f compartments which allow significant post-transcriptional modification to occur before the mature transcript exits the nucleus.
    - Examples; removing introns for RNA transcript
The immediate product of mRNA transcription is referred to as pre-mRNA.
- It must go through several stages of post-transcriptional modification to become mature mRNA
- One of the stages is called RNA splicing
  - Introns ( Intervening sequences) Is a sequence interspersed throughout the mRNA that will not contribute to the formation of polypeptides.
    - They must be removed
  - Exons are the remaining coding portions after the removal of introns.
    - Will be spliced together to form the mature mRNA.
The post-transcriptional modification also includes:
- An addition of a 5' cap; usually occurs before transcription s been completed.
  - A poly-A tail os added after transcription has been made.

7.2 - Transcription and gene expression