Hoofdstuk 17 2008 deel 2

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Hoofdstuk 17 2008 deel 2

  1. 1. Outline <ul><li>From gene to protein </li></ul><ul><li>Transcription </li></ul><ul><ul><li>Initiation </li></ul></ul><ul><ul><li>Elongation </li></ul></ul><ul><ul><li>Termination </li></ul></ul><ul><li>RNA processing </li></ul><ul><li>Protein synthesis </li></ul><ul><ul><li>Initiation </li></ul></ul><ul><ul><li>Elongation </li></ul></ul><ul><ul><li>Termination </li></ul></ul><ul><li>Effect of mutations on proteins </li></ul>
  2. 2. Role of nucleotides <ul><li>DNA </li></ul><ul><ul><li>double-stranded nucleotide chain </li></ul></ul><ul><li>RNA: Transcription </li></ul><ul><ul><li>single-stranded nucleotide chain </li></ul></ul><ul><ul><li>rRNA </li></ul></ul><ul><ul><li>tRNA </li></ul></ul><ul><ul><li>mRNA </li></ul></ul><ul><ul><li>other RNAs </li></ul></ul>5’ 3’
  3. 3. 5.27 Similarity and difference RNA-DNA
  4. 4. 5.27 Similarity and difference RNA-DNA
  5. 5. 5.27 Similarity and difference RNA-DNA
  6. 6. RNA synthesis <ul><li>Catalysed by </li></ul><ul><ul><li>RNA polymerase </li></ul></ul><ul><ul><li>initiation proteins </li></ul></ul><ul><li>Sequence of RNA determined by template </li></ul><ul><ul><li>the template strand of DNA </li></ul></ul><ul><li>RNA pol synthesizes new RNA from 5’  3’ </li></ul>ATP+CTP+GTP+UTP (=NTPs)  RNA + PPi (  2Pi) 3’ 5’ 3’ 5’ sense strand template strand Direction of transcription
  7. 7. RNA synthesis <ul><li>Catalysed by </li></ul><ul><ul><li>RNA polymerase </li></ul></ul><ul><ul><li>initiation proteins </li></ul></ul><ul><li>Sequence of RNA determined by template </li></ul><ul><ul><li>the template strand of DNA </li></ul></ul><ul><li>RNA pol synthesizes new RNA from 5’  3’ </li></ul>ATP+CTP+GTP+UTP (=NTPs)  RNA + PPi (  2Pi) 3’ 5’ 3’ 5’ sense strand template strand Direction of transcription
  8. 8. Promotor and TATA-box <ul><li>Promoter is site on DNA where RNA pol binds </li></ul><ul><li>+1 indicates bp where RNA pol starts transcription </li></ul><ul><li>In coli : two boxes, one at -35 and the TATAA box on -10 </li></ul><ul><li>In eukaryotes, many boxes, and a TATAA box around -35 </li></ul><ul><li> promoter sequences are transcribed into RNA </li></ul>never never
  9. 9. Promotor and TATA-box <ul><li>Promoter is site on DNA where RNA pol binds </li></ul><ul><li>+1 indicates bp where RNA pol starts transcription </li></ul><ul><li>In coli : two boxes, one at -35 and the TATAA box on -10 </li></ul><ul><li>In eukaryotes, many boxes, and a TATAA box around -35 </li></ul><ul><li> promoter sequences are transcribed into RNA </li></ul>never never
  10. 10. <ul><li>Start of transcription </li></ul><ul><ul><li>DNA sequences on defined places </li></ul></ul><ul><ul><ul><li>TATAA-box </li></ul></ul></ul><ul><ul><li>Synthesis of RNA (nearly) always after promotor </li></ul></ul>9 Promoter and terminator in pro- and eukaryote
  11. 11. 7 Synthesis of RNA
  12. 12. 7 Synthesis of RNA
  13. 13. 7 Synthesis of RNA
  14. 14. 7 Synthesis of RNA
  15. 15. 7: Elongation of transcription <ul><li>Sequence of RNA matches that of sense-strand of DNA </li></ul><ul><ul><li>U for T </li></ul></ul><ul><ul><li>ribose –deoxyribose </li></ul></ul><ul><li>New nucleotides are added at 3’ end of RNA </li></ul>
  16. 16. Composition of E. coli RNA polymerase <ul><li>RNA polymerase binds DNA </li></ul><ul><ul><li>Sigma (  ) subunit binds DNA </li></ul></ul><ul><li>Starts transcription on DNA </li></ul><ul><li>Makes RNA </li></ul>
  17. 17. Transcription movie Movies Deze kun je via WebCT bekijken. Neem contact op met de docent als dat problemen geeft.
  18. 18. 8: Initiation of eukaryotic transcription <ul><li>Promoter: </li></ul><ul><ul><li>site where RNA pol binds </li></ul></ul><ul><ul><li>TATAA-box </li></ul></ul><ul><li>Proteins required: </li></ul><ul><ul><li>transcription factors (proteins!) </li></ul></ul><ul><ul><li>RNA pol </li></ul></ul>
  19. 19. 8: Initiation of eukaryotic transcription <ul><li>Transcription factors </li></ul><ul><ul><li>DNA binding proteins </li></ul></ul><ul><li>RNA polymerase </li></ul><ul><li>More in Chapter 19 </li></ul>
  20. 20. 8: Initiation of eukaryotic transcription <ul><li>Transcription factors </li></ul><ul><ul><li>DNA binding proteins </li></ul></ul><ul><li>RNA polymerase </li></ul><ul><li>More in Chapter 19 </li></ul>
  21. 21. Termination of transcription <ul><li>Signal in newly made RNA </li></ul><ul><li>Prokaryotes: </li></ul><ul><ul><li>sequence in RNA leads to dissociation of complex </li></ul></ul>
  22. 22. Termination of transcription <ul><li>Signal in newly made RNA </li></ul><ul><li>Prokaryotes: </li></ul><ul><ul><li>sequence in RNA leads to dissociation of complex </li></ul></ul><ul><li>Eukaryotes: </li></ul><ul><ul><li>Polyadenylation sequence AAUAAA in RNA activates </li></ul></ul><ul><ul><ul><li>RNA endonuclease </li></ul></ul></ul><ul><ul><ul><li>polyA polymerase </li></ul></ul></ul><ul><ul><li>adding of 200-250 A-nucleotides to newly created 3’end </li></ul></ul><ul><ul><li>one of the 3 steps in RNA processing </li></ul></ul>
  23. 23. Outline <ul><li>From gene to protein </li></ul><ul><li>Transcription </li></ul><ul><ul><li>Initiation </li></ul></ul><ul><ul><li>Elongation </li></ul></ul><ul><ul><li>Termination </li></ul></ul><ul><li>Eukaryotic RNA processing </li></ul><ul><li>Protein synthesis </li></ul><ul><ul><li>Initiation </li></ul></ul><ul><ul><li>Elongation </li></ul></ul><ul><ul><li>Termination </li></ul></ul><ul><li>Effect of mutations on proteins </li></ul>
  24. 24. 9: Two RNA-processing steps <ul><li>Capping (methylated GTP 5’-5’) </li></ul><ul><ul><li>Uncapped mRNA very unstable, protection against RNases </li></ul></ul><ul><ul><li>Required for protein synthesis (later) </li></ul></ul><ul><li>Addition of poly-A tail </li></ul><ul><ul><li>Required for stability </li></ul></ul><ul><ul><li>Required for protein synthesis (later) </li></ul></ul><ul><li>5’UTR= 5’ untranslated region </li></ul>3’UTR= 3’ untranslated region
  25. 25. What is a cap-structure? Essential cell biology, Alberts et al.
  26. 26. What is a cap-structure? Essential cell biology, Alberts et al.
  27. 27. 10: Third processing step: splicing <ul><li>Most genes have long non-coding sequences </li></ul><ul><ul><li>in trons (remain in nucleus) </li></ul></ul><ul><ul><li>ex ons ex it nucleus </li></ul></ul>5’CAP is only one nucleotide, and Cap belongs to first exon..…

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