La DNA Polimerasi può commettere errori

1. La DNA Polimerasi può commettere errori • Nei batteri: 1 errore ogni 109 basi in ogni generazione

2. La correzionedelle bozze

3. Le basi si possono alterare spontaneamente

4. CorrezionedelleBozze n2

5. Alterazioni del DNA indotte da agenti fisici

6. AlterazionidaAgentiChimici

7. Il DNA danneggiatoviene riparato

8. Due sistemi di riparazione

9. Mammalian Cells* α β† γ δ ε Polymerization: 5′ → 3′ + + + + + Exonuclease proofreading activity:‡ 3 → 5′ − − + + + Synthesis from:      RNA primer + − − + ?      DNA primer + + + + + Associated DNA primase + − − − − Sensitive to aphidicolin (inhibitor of cell DNA synthesis) + − − + + Cell location:      Nuclei + + − + +      Mitochondria − − + − − *Yeast DNA polymerase I, II, and III are equivalent to polymerase α, β, and δ, respectively. I and III are essential for cell viability.†Polymerase β is most active on DNA molecules with gaps of about 20 nucleotides and is thought to play a role in DNA repair.‡FEN1 is the eukaryotic 5′ → 3′ exonuclease that removes RNA primers; it is similar in structure and function to the domain of E. coli polymerase I that contains the 5′ → 3′ exonuclease activity. Le DNA polimerasi sono tante

10. Malattie ereditarie legate a difetti della riparazione del DNA

11. Classificazione del DNA Eucariotico • Protein-coding genes Solitary genes Duplicated and diverged genes (functional gene families and nonfunctional pseudogenes) • Tandemly repeated genes encoding rRNA, 5S rRNA, tRNA, and histones • Repetitious DNA Moderately repeated DNA (mobile DNA elements) • Transposons • Viral retrotransposons Simple-sequence DNA (Satellite DNA: eg telomeres) Long interspersed elements (LINES; nonviral retrotransposons) Short interspersed elements (SINES; nonviral retrotransposons) • Unclassified spacer DNA

12. Classificazione del DNA Eucariotico

13. Genomi a Confronto

14. Struttura “tipo” di un Cromosoma Umano