1 / 39

Understanding DNA Replication, Transcription, and Translation in Molecular Biology

This comprehensive overview covers the essential processes of DNA replication, transcription, and translation. It highlights the roles of key components such as the replisome, RNA polymerase, and ribosomes, and explains the significance of various mutations, including point mutations and larger genomic changes. The text delves into the mechanics of gene expression, emphasizing how these processes contribute to laboratory techniques and diagnostic applications, including the clinical implications of hereditary diseases such as sickle-cell and cystic fibrosis.

vincent-hernandez
Télécharger la présentation

Understanding DNA Replication, Transcription, and Translation in Molecular Biology

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Replication (cont.) 14N 15N Meselson, Stahl - 1958

  2. Replication (cont.) • Replication Fork • Prokaryotes • Eukaryotes • Ingredients • Replisome • dNTPs • Template ssDNA • Energy to form bond • Hydrolysis of extra phosphates • Add 5’ to 3’-end of hanging hydroxyl

  3. Replication (cont.) • Replicons • Prokaryotes • Eukaryotes • Replisome components • DnaB, DnaG, Pol III, SSBs • Semi-discontinuous Synthesis • Leading and lagging • Okazaki fragments • Ligase

  4. Replication (cont.)

  5. Replication (cont.) • Why is replication important to a lab tech? • Mutations • Point mutations - nonsense, missense, silent • Transitions (G:C to A:T) • Transversions (A:T to T:A) • Sickle-cell disease - due to missense point mutation in beta Hgb gene (valine inserted over glutamic acid) • Base mispairing (e.g., A:C?) • Deletions/Insertions (e.g., transposons)

  6. Transcription

  7. Transcription • Proteins aren’t made in nucleus • Need transition medium for passing information • Messenger RNA (mRNA) to rescue! • Differences in DNA and RNA • Pentose used  Ribose (2’ carbon) • Pyrimidine used  Uracil vs. Thymine • Single-stranded; can bond with itself • Classes: mRNA, rRNA, tRNA, RNAi

  8. Transcription (cont.) • 4 phases • Initiation • Elongation • Termination • Post-transcriptional mods

  9. Transcription (cont.) • Transcription Bubble • Melt • Dock/Initiate • Extend • Close • Transcript unstable • 5’-methylated guanosine cap • Poly-A tail • Protects against exonucleases • Transcript transported outside nucleus

  10. SENSE doesn’t make sense

  11. Transcription (cont.) • Post-transcriptional modifications • Keeping “tasty bits” • Exons - Conserved • Selective pressure • Introns - Not conserved • Lack of selective pressure • Remove these!

  12. Transcription (cont.)

  13. Transcription (cont.) Polymerase mRNA

  14. Transcription (cont.) • Why is transcription important to lab techs? • Pathology can erupt all along Central Dogma • Mutations! • Natural background mutation rate • Repair mechanisms • Molecular basis of evolution • Mutations can be advantageous or problematic • Sickle-cell disease • Cystic fibrosis • Mutations that cause HIV resistance?

  15. Translation

  16. Translation Polymerase Ribosome mRNA

  17. Translation (cont.)

  18. Translation Codons Ribosome

  19. Translation • How is protein made from mRNA? • Protein synthesis  ribosome • mRNA transcript contains codons • 3-base triplet synonymous for certain amino acid • ORF (open reading frame) • Each amino acid may have >1 corresponding codon • Other way around? NO!

  20. Translation (cont.)

  21. Translation (cont.) • Each codon has matched tRNA • Amino acid attaches to tRNA

  22. Translation (cont.) Tertiary Secondary Primary?

  23. Translation (cont.)

  24. Translation (cont.)

  25. Translation (cont.) • 4 phases • Initiation • Elongation • Termination • Post-translational mod? • Amino acid structure • +NH3-CH[R]-COO-

  26. Translation (cont.)

  27. Translation (cont.) A A E E P P

  28. Translation (cont.)

  29. Translation (cont.) • Structural levels • Primary • Secondary • Tertiary • Quaternary

  30. Translation (cont.)

  31. Translation (cont.)

  32. Translation (cont.)

  33. Translation (cont.)

  34. Translation (cont.)

  35. Translation (cont.)

  36. Translation (cont.)

  37. Translation (cont.)

  38. Translation (cont.) • Why is translation important to lab techs? • Protein basis for many traditional lab assays • Protein electrophoresis • Hemoglobinopathies • Sickle (quality) • Thalassemias (quantity) • Enzyme kinetics assays • CK, LDH, lipase, amylase, etc. • Colorimetric assays • Total protein, albumin • Lipoproteins • All proteins have genetic origin • Errors in translation/post-translation mods

More Related