Prokaryotic & Eukaryotic Transcription Units: Similarities and Differences explained
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Prokaryotic Transcription Unit
- The Prokaryotic Transcription Unit has a Promoter element and a coding region.
- RNA Polymerase binds to the Promoter region
- Starts transcribing at +1 region
- Reads from 3’ to 5’ and synthesizes 5’ to 3’.
- UTRs are the untranslated regions.
- At terminator sequence mRNA is released.
- At the end of transcription, we get an mRNA that has 5’ to 3’ end.
- At the 5’ end there is 5’ UTR and at 3’ there is 3’UTR.
- In between, there is a coding region that contains the proteins and amino acids information.
Facts about Prokaryotic mRNA
- It may or may not be Polycistronic many that it may contain one or more coded genes on one mRNA.
- There are no Introns-intervening sequences.
- Transcription and Translation are coupled.
- As soon as the mRNA is synthesized it binds with ribosome and starts translating.
*Remember the ribosome is the only structure that READS from 5′ to 3′. Otherwise all the Reading is always from 3′ to 5′.
Protein is synthesized from Amino to Carboxy terminus.
- How does ribosome know where to bind and, where to initiate translation?
Eukaryotic Transcription Unit
- The Eukaryotic Transcritption unit is similar to the Prokaryotic unit but with some differences.
- It also has a promotor region for RNA Polymerase.
- RNA Polymerase initiates the transcription at the +1 site.
- A RNA copy of the DNA is made by this process.
- The template strand is used to transcribe.
- RNA Polymerase reads the template strand from 3′ to 5′ and synthesizes complimentary.
- Each gene is more widely spaced and each has its own promotor and terminator region.
- No polycistronic messages. It is Monocistronic.
- Promoter elements, the TATA box the CAAT box are attached to the coding strand.
- Each gene is more …
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