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Differentiate between the process of transcription in prokaryotes and eukaryotes ?

Asked by S. Girija(student) , on 20/1/13

EXPERT ANSWER

Transcription is the process of formation of RNA from DNA.

 

In prokaryotes: 

  • The structural genes are polycistronic and continuous.
  • A single DNA dependent RNA polymerase catalyses the transcription of all three types of RNA that is mRNA, tRNA & rRNA
  • The DNA strands unwind and one of the strands (3' → 5’) acts as the template strand.
  • The RNA polymerase binds at the promoter site for transcription.
  • It uses ribonucleotides for polymerization on a DNA template following complementary of bases.
  • As unwinding continues, the new strand of RNA also elongates. Polymerisation occurs in the 5’ →  3’ direction.
  • When RNA polymerase falls on the terminator sequence, the synthesis stops and the new RNA strand is liberated.

 

         In Eukaryotes:

  • The structural genes are split.
  • They have exons interspread with introns. (the coding and non coding sequence respectively)
  • The primary transcript of RNA undergoes splicing , by which the introns are removed and the exons are joined together.
  • The hn RNA undergoes two additional processes called, capping and tailing to become mRNA.
  • Methyl guanosine tri phosphate is added to the 5’ end of hn RNA in capping.
  • Adenylate residues (about 200 – 300) are added at the 3’ end in tailing.
  • The fully processed hn RNA is called mRNA is released from the nucleus into the cytoplasm.

 

Posted by G. Lakshmi (MeritNation Expert)on 21/1/13

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