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Explore the first steps of gene expression, the differences between DNA and RNA, and how RNA molecules play a role in systemic lupus erythematosus (SLE). Learn about RNA structure, secondary structure, nucleotide differences, splicing, and genetic disorders like β-thalassemia.

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  1. transcription The first step of gene expression – synthesis of RNA molecule

  2. Some nomenclature conventions RNAP

  3. RNA DNA

  4. Similarities and Differences Between DNA and RNA RNA DNA • Similar strand structure • Can define a 5’ and 3’ end • 2’ hydroxyl in RNA: causes stability differences) • Uracil in RNA takes the place of Thymine in in DNA

  5. Secondary structure of RNA Stem & loop

  6. Difference between DNA and RNA. • DNA – Double Helix, RNA – Single Stranded • DNA --- A-T, RNA ---A-U • DNA ---Deoxyribose Sugar, RNA---Ribose • What is a similarity of DNA and RNA? • G binds with C in both DNA and RNA • Both have sugar and phosphate backbone

  7. The pathway of gene expression

  8. CAP

  9. Conserved seqences Polypyrimidine tract

  10. גן הבטא גלובין ההומני

  11. Splice sites can be included in the exons

  12. mRNA splicing lariat

  13. spliceosome מעגל מחזורי של ראקציית השיחבור ספליסוזום

  14. Systemic Lupus Erythematosus (SLE) Lupus is a type of immune system disorder known as an autoimmune disease. In autoimmune diseases, the body harms its own healthy cells and tissues. This leads to inflammation and damage of various body tissues. Lupus can affect many parts of the body, including the joints, skin, kidneys, heart, lungs, blood vessels, and brain. Although people with the disease may have many different symptoms, some of the most common ones include extreme fatigue, painful or swollen joints (arthritis), unexplained fever, skin rashes, and kidney problems. Lupus is also known as a rheumatic disease. The rheumatic diseases are a group of disorders that cause aches, pain, and stiffness in the joints, muscles, and bones. 

  15. 15% of the mutation leading to genetic disorders effect splicing activity Untreated βthalassemia

  16. Treatment of thalassemia major

  17. antisense

  18. Human genome 2.91 billion base pairs 24,500 genes 1.5% exons (127 nucleotides) 24% introns (~3,000 nucleotides) 75% intergenic (no genes) Average size of a gene is 27,894 bases Contains an average of 8.8 exons Titin contains 234 exons.

  19. Gene number C. elegans 19,000~ Drosophila melanogaster ~13,600 Arabidopsis thaliana 25,500~ Mouse ~24,000 Homo Sapiens ~24,000 Rice (Oryza sativa) ~50,000

  20. Compared to worm and fly, human has shorter exons and longer introns on the extremes of the distribution 150 nt – drosophila 125 nt – Ciona intes. 119 nt - human

  21. 5000 genes 234 introns Multi-introns genes 7.8 introns per gene

  22. Sequences of human-mouse homologous exons are 88% conserved

  23. Alternative splicing Alternative splicing פוליפרימידין טראק 40% 18% 8% ? 3% isoform

  24. 1 18 איזופורמים

  25. Alternative splicing regulate pro or anti apoptotic pathways. pro-apoptotic anti-apoptotic

  26. translation The last stage in gene expression – synthesis of protein

  27. Amino acid

  28. C N

  29. N to C terminal 5’ to 3’

  30. CDS

  31. tRNA Aminoacyl

  32. tRNA • Aminoacyl-tRNA synthetase (20 diffrent) • one for each amino acid • NEEDS ENERGY!

  33. 64 combinations for 20 amino acids 3 termination codons

  34. סרט טרנסלציה ספירת מלאי Met one codon LEU 6 codons, 4 of which are CUN

  35. Disease-Associated Mutations A mutation is a change in the normal base pair sequence Commonly used to define DNA sequence changes that alter protein function

  36. Polymorphism DNA sequence changes that do not alter protein function (common definition, not technically correct) Functional protein Functional protein

  37. G A A G U U U U G G U U G G A U U C G G C C A A A A U U C A A U U Met Met Leu Leu Ala Gln Gln Lys Phe Phe Gly G G G A U A Lys Gly Single nucleotide polymorphisms (SNP) (in the coding sequence) mRNA Protein Normal G G A C Ala Sequence variant mRNA Protein Silent DNA sequence polymorphism

  38. G A A G U U U U G G U U G G A U U C G G C C A A A A U U C A A U U Met Met Leu Leu Ala Gln Gln Lys Phe Phe Gly G A A Lys Missense Mutations mRNA Protein Normal mRNA Protein Missense G A G C A C Ala Ser Missense: changes to a codon for another amino acid (can be harmful mutation or neutral polymorphism)

  39. G A A G A U U G G U G U C G C A A U C A U Lys Met Leu Ala Gln Phe Gly G A G U U G G U G U U C G A A U C U C A A Met Nonsense Mutations mRNA Protein Normal mRNA Protein Nonsense Nonsense: change from an amino acid codon to a stop codon, producing a shortened protein

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