Hoofdstuk 17 2008 deel 3

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Hoofdstuk 17 2008 deel 3

  1. 1. 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..…
  2. 2. 11: How is splicing done? The Campbell version <ul><li>snRNP “snurp” </li></ul><ul><ul><li>small ribonucleoproteins </li></ul></ul><ul><ul><ul><li>RNA and protein </li></ul></ul></ul><ul><ul><li>recognize splice sequences </li></ul></ul><ul><ul><li>assemble into </li></ul></ul><ul><li>Spliceosome </li></ul><ul><li>Excised intron=lariat </li></ul><ul><li>(‘lasso’) </li></ul><ul><li>Due to ‘branchpoint’ </li></ul>
  3. 3. Splicing from Alberts, Essential cell biology <ul><li>snRNP “snurp” </li></ul><ul><ul><li>Small ribonucleoproteins </li></ul></ul><ul><ul><ul><li>RNA and protein </li></ul></ul></ul><ul><ul><li>Recognize splice sequences </li></ul></ul><ul><ul><li>Assemble into </li></ul></ul><ul><li>Spliceosome </li></ul><ul><li>Excised intron </li></ul><ul><ul><li>Lariat(‘lasso’) </li></ul></ul><ul><ul><ul><li>Due to ‘branchpoint’ </li></ul></ul></ul>
  4. 4. 11: How is splicing done? The Campbell version <ul><li>snRNP “snurp” </li></ul><ul><ul><li>small ribonucleoproteins </li></ul></ul><ul><ul><ul><li>RNA and protein </li></ul></ul></ul><ul><ul><li>recognize splice sequences </li></ul></ul><ul><ul><li>assemble into </li></ul></ul><ul><li>Spliceosome </li></ul><ul><li>Excised intron=lariat </li></ul><ul><li>(‘lasso’) </li></ul><ul><li>Due to ‘branchpoint’ </li></ul>
  5. 5. Splicing without proteins? <ul><li>pre RNAs can in some cases perform splicing without assistance from outside </li></ul><ul><ul><li>catalytic activity in RNA itself! </li></ul></ul><ul><li>“ All biological catalysts are proteins” </li></ul><ul><ul><li>RNA as catalyst </li></ul></ul><ul><ul><li>see later also peptide bond formation by RNA </li></ul></ul>
  6. 6. 12: Function of splicing <ul><li>Domain structure </li></ul><ul><ul><li>Exon shuffling </li></ul></ul>
  7. 7. 12: Function of splicing <ul><li>Domain structure </li></ul><ul><ul><li>Exon shuffling </li></ul></ul><ul><li>Alternative splicing </li></ul>18.11
  8. 8. 11: How is splicing done? The Campbell version <ul><li>snRNP “snurp” </li></ul><ul><ul><li>small ribonucleoproteins </li></ul></ul><ul><ul><ul><li>RNA and protein </li></ul></ul></ul><ul><ul><li>recognize splice sequences </li></ul></ul><ul><ul><li>assemble into </li></ul></ul><ul><li>Spliceosome </li></ul><ul><li>Excised intron=lariat </li></ul><ul><li>(‘lasso’) </li></ul><ul><li>Due to ‘branchpoint’ </li></ul>
  9. 9. Exon definitie <ul><li>Exon: dat deel van het pre-mRNA dat naar het cytoplasma gaat </li></ul>
  10. 10. Types of RNA in eukaryotes
  11. 11. 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>
  12. 12. The ribosome: a protein synthesis machine <ul><li>Ribosome translates mRNA into protein </li></ul><ul><ul><li>ribosome is structure containing proteins and RNA </li></ul></ul><ul><ul><ul><li>ribosomal RNA or rRNA </li></ul></ul></ul>Amino acids+ATP+GTP  protein + AMP+GDP +Pi
  13. 13. 13: Basic concept of translation <ul><li>aa is added to chain by code in mRNA </li></ul><ul><li>transferred by tRNA </li></ul><ul><ul><li>transfer RNA </li></ul></ul>
  14. 14. 13: Basic concept of translation <ul><li>aa is added to chain by code in mRNA </li></ul><ul><li>transferred by tRNA </li></ul><ul><ul><li>transfer RNA </li></ul></ul><ul><li>This arrow indicates mRNA movement!! </li></ul><ul><ul><li>Be clear! </li></ul></ul>
  15. 15. 14: Translators <ul><li>tRNA </li></ul><ul><ul><li>cloverleaf in 2D </li></ul></ul><ul><ul><li>unusual nt </li></ul></ul><ul><ul><li>intrachain basepairing </li></ul></ul><ul><li>aminoacyl-tRNA synthetase </li></ul><ul><li>ribosome </li></ul>
  16. 16. 14: 3D model of tRNA <ul><li>75-80 nucleotides </li></ul><ul><li>64 tRNAs???? No </li></ul><ul><li>aa attachment site </li></ul><ul><li>anticodon </li></ul><ul><li>L-shape </li></ul><ul><li>brings aa to ribosome </li></ul><ul><li>translates nt-language into aa language </li></ul>
  17. 17. 15: Coupling aa to tRNA <ul><li>Aminoacyl-tRNA synthetase </li></ul><ul><ul><li>Aminoacyl- is from aminoacid </li></ul></ul><ul><li>2 stages </li></ul><ul><ul><li>Activation of aa </li></ul></ul><ul><ul><li>Coupling of activated aa to tRNA </li></ul></ul><ul><ul><li>Driven by hydrolysis of PPi </li></ul></ul>
  18. 18. (bord) <ul><li>Arg-tRNA </li></ul>Arg Cys-tRNA Arg Arg-tRNA tRNA Arg

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