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Gene transcription,post-transcriptional processing & reverse transcription

Gene transcription,post-transcriptional processing & reverse transcription. Concept A. Enzymes involved in transcription a. RNA polymerase ( DNA-dependent RNA polymerase,DDRP ). require: (1) four NTP (2) Mg 2+ or Mn 2+ (3) DNA template

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Gene transcription,post-transcriptional processing & reverse transcription

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  1. Gene transcription,post-transcriptional processing & reverse transcription

  2. Concept • A. Enzymes involved in • transcription • a. RNA polymerase • ( DNA-dependent RNA • polymerase,DDRP )

  3. require: (1) four NTP (2) Mg 2+ or Mn 2+ (3) DNA template (4) synthesis direction

  4. Products: single strand RNA containing DNA heredity information

  5. RNA pol in prokaryotes • ( E.coli RNA polymerase ) • * functions • * constitute • four subunites

  6. core enzyme & holoenzyme • RNA pol in eukaryotes

  7. RNA pol in eukaryotes

  8. Type I II III location nucleoli nucleoplasm ucleoplasm products 18s,5.8s, pre-mRNA, RNA,5sRNA 28s rRNA hnRNA U6 sensitivity none +++ + to a amantin

  9. B. Process of transcription initiation, elongation, termination a. the initiation stage • promoter * concept * characteristics

  10. *Promoter of prokaryotes -10bp-------TATAAT (TATA box) (pribnow box) -35bp------- TTGACA

  11. Promoter of eukaryote -25bp-------TATAAT (TATA box) (hogness box -40bp------- GCbox -110bp-----CAAT box

  12. -110 -40 -25 +1 CCAAT box GC box TATA box

  13. GC or CAAT box both in sense or antisense strand all effective

  14. antisense strand (template strand, (-)strand,) Sense strand (coding strand,(+)strand)

  15. DNA: antisense 5’AACGTTACCGATC 3’ 3’TTGCAATGGCTAG 5’ sence mRNA UUGCAAUGGCUAG

  16. • synthesis direction 5’ 3’ • characteristic of transcription----- asymmetrical transcription

  17. • enhancer *concept * characteristics

  18. • cis -acting element *concept • trans-acting element *concept

  19. b.elongation stage • the transcription products elongate along the 5’to 3’

  20. • the RNA pol moves along the 3’ to 5’ • 50 nucleotides/second/per molecular enzyme

  21. • newly synthesis DNA-RNA hybridized strand is unsteadiness

  22. C.termination * concept *the type of termination a.Rho()-dependent termination

  23. *the structure of Rho factor *the functure of Oho factor

  24. b.Rho()-independent termination the special region in the DNA template

  25. B.inhibitors of transcription E.summarize a.RNA pol b.process

  26. initiation elongation termination c. characteristics of transcription

  27. d. the different of mRNA transcription in prokayotes & eukaryotes

  28. Prokaryotes eukaryotes Policistronic transcript monocistronic transcrip Transcription coupled with translation seprate No processing processing Shorter half life longer half life

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