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Fig. 7-1

Chapter 7: DNA structure and replication. Fig. 7-1. FROM GENE TO PROTEIN Replication : DNA-dependent DNA synthesis; DNA polymerase and associated proteins; DNA template, dNTPs Transcription : DNA-dependent RNA synthesis; RNA polymerase and associated proteins; DNA template, NTPs

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Fig. 7-1

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  1. Chapter 7: DNA structure and replication Fig. 7-1

  2. FROM GENE TO PROTEIN Replication: DNA-dependent DNA synthesis; DNA polymerase and associated proteins; DNA template, dNTPs Transcription: DNA-dependent RNA synthesis; RNA polymerase and associated proteins; DNA template, NTPs Translation: RNA-dependent polypeptide synthesis; ribosome and associated molecules; mRNA, ribosomes, aminoacyl-tRNA

  3. Griffith (1928): Streptococcal transformation Fig. 7-2

  4. Avery, MacLeod & McCarty (1944): Griffith’s “transforming principle” is DNA Fig. 7-3

  5. Fig. 7-5

  6. Background information available • to Watson & Crick in construction • of their double-helical DNA model • E. Chargaff’s “rule” (A=T, G=C)

  7. Background information available • to Watson & Crick in construction • of their double-helical DNA model • E. Chargaff’s “rule” (A=T, G=C) • Wilkins & Franklin’s x-ray diffraction • data (suggested strongly helical, • probably double-helical structure)

  8. Major groove Minor groove Fig. 7-8

  9. Fig. 7-8

  10. DNA double helix is stabilized by: • Hydrophobic interactions among bases • 2. Hydrophilic interactions of PO4 with aqueous environment • 3. Hydrogen bonds between complementary • bases (A-T pair, two H bonds; G-C pair, • three H bonds)

  11. Potential modes of DNA replication Fig. 7-12

  12. Fig. 7-13

  13. 5’-3’ synthesis of DNA proceeds by 3’ extension and complementary base pairing Fig. 7-15

  14. Replication fork dynamics creates polarity problems in lagging strand synthesis Fig. 7-16

  15. Fig. 7-17

  16. Replication fork dynamics depends upon cooperative activities of a variety of proteins Fig. 7-18

  17. Chromosome replication is carried out by expansion of “bubbles” Fig. 7-22

  18. DNA synthesis creates problems at chromosome ends Ever-shortening 5’ ends Fig. 7-24

  19. Telomerase is special DNA polymerase that maintains chromosome ends Fig. 7-25 Telomeres consist of high-copy number, simple sequence repeats

  20. Fig. 7-

  21. Human haploid genome  1 m of DNA (about 2 m DNA per somatic cell*) (about 4.3 cm DNA per chromosome) *~1013 somatic cells per average human ~ 2 x 1013 m of DNA per average human (nearly 100 round trips to the sun!!)

  22. Human haploid genome  1 m of DNA (about 2 m DNA per somatic cell*) (about 4.3 cm DNA per chromosome) *~1013 somatic cells per average human ~ 2 x 1013 m of DNA per average human (nearly 100 round trips to the sun!!) Average human nucleus ~ 6 μm diameter Eukaryotic DNA is densely packaged

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