Introduction to DNA structure

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Introduction to DNA structure

  1. 1. mRNA Transcription Introduction The Central Dogma of Molecular Biology Cell Polypeptide (protein) Translation Ribosome Reverse tanscription DNA
  2. 2. DNA STRUCTURE chemical structure of the 4 nucleotides in DNA
  3. 3. DNA STRUCTURE  hydrogen bonded nucleotides on opposite helices  DNA helices are antiparallel  carbons on sugar define ends... 5' and 3'  pyrimidines bond with purines  T  A  C  G
  4. 4. DNA STRUCTURE  bonding is specific: pyrimidines bond with purines  implication: means for accurate replication
  5. 5. DNA STRUCTURE  helical structure of DNA  major & minor groves  10Å radius & 20Å diameter  3.4Å between nucleotide base pairs  34Å / 360° turn  10 nucleotide base pairs / 360° turn
  6. 6. A T T A G C C G G C TA T A G C C G G C T A A T Packaging DNA Histone proteins Histone octomer B DNA Helix 2 nm
  7. 7. A T T A G C C G G C TA T A G C C G G C T A A T Packaging DNA Histone proteins B DNA Helix Histone octomer 2 nm
  8. 8. A T T A G C C G G C TA T A G C C G G C T A A T Packaging DNA Histone proteins Histone octomer Nucleosome 11 nm B DNA Helix 2 nm
  9. 9. Packaging DNA A TA C G C G G C T A A T
  10. 10. Packaging DNA A TA C G C G G C T A A T
  11. 11. Packaging DNA A TA C G C G G C T A A T Protein scaffold 11 nm“Beads on a string” 30 nm Tight helical fiber Looped Domains200 nm
  12. 12. Packaging DNA G C A T Protein scaffold Metaphase Chromosome 700 nm 11 nm 30 nm 200 nm 2 nm Looped Domains Nucleosomes B DNA Helix Tight helical fiber
  13. 13. Replication Chromosomes, Chromatids and Centromeres Centromere Chromosome arm Chromosome arm Identical chromatid Chromatid Anaphase A packaged chromosome Two identical chromosomes
  14. 14. Chromosome Morphology Chromosome arm Chromosome arm Centromere Submetacentric Acrocentric TelocentricMetacentric q arm p arm petite Chromosomes can be distinguished on the basis of size and the relative location of centromeres.
  15. 15. Human karyotype (of a man with a normal 46,XY constitution)

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