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Chapter 10 DNA Replication and Recombination

Chapter 10 DNA Replication and Recombination. Chapter Contents. 10.1 DNA Is Reproduced by Semiconservative Replication 10.2 DNA Synthesis in Bacteria Involves Five Polymerases, as well as Other Enzymes 10.3 Many Complex Tasks Must Be Performed during DNA Replication

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Chapter 10 DNA Replication and Recombination

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  1. Chapter 10 DNA Replication and Recombination

  2. Chapter Contents 10.1 DNA Is Reproduced by Semiconservative Replication 10.2 DNA Synthesis in Bacteria Involves Five Polymerases, as well as Other Enzymes 10.3 Many Complex Tasks Must Be Performed during DNA Replication 10.4 A Summary of DNA Replication in Prokaryotes 10.5 Replication in Prokaryotes Is Controlled by a Variety of Genes Continued

  3. 10.6 Eukaryotic DNA Synthesis Is Similar to Synthesis in Prokaryotes, but More Complex 10.7 Telomeres Provide Structural Integrity at Chromosome Ends but are Problematic to Replicate 10.8 DNA Recombination, Like DNA Replication, Is Directed by Specific Enzymes 10.9 Gene Conversion Is a Consequence of DNA Recombination

  4. Section 10.1: DNA Is Reproduced by Semiconservative Replication • The complementarity of DNA strands allows each strand to serve as a template for synthesis of the other. (Figure 10.1)

  5. Section 10.1 • Three possible modes of DNA replication are possible: • conservative • semiconservative • dispersive (Figure 10.2)

  6. Figure 11.2

  7. Section 10.1 • The Meselson-Stahl experiment demonstrated that: • DNA replication is semiconservative • each new DNA molecule consists of one old strand and one newly synthesized strand (Figure 10.3 and Figure 10.4)

  8. Section 10.1 • The Taylor-Woods-Hughes experiment demonstrated that DNA replication is semiconservative in eukaryotes (Figure 10.5)

  9. Section 10.1 • DNA replication begins at the origin of replication and is bidirectional rather than unidirectional (Figure 10.6).

  10. Section 10.1 • A replicon is the length of DNA that is replicated following one initiation event at a single origin. Replication Fork

  11. Section 10.2: DNA Synthesis in Bacteria Involves Five Polymerases, as well as Other Enzymes • DNA polymerase catalyzes DNA synthesis and requires a DNA template and all four dNTPs (Figure 10.7).

  12. Abbreviations/Vocabulary • -ase = enzyme. Proteins that act as biological catalysts increase the number and frequency of chemical reactions. • dNMP = deoxy Nucleoside Mono Phosphate • dNDP= deoxy Nucleoside Di Phosphate • dNTP = deoxy Nucleoside Tri Phosphate

  13. Nucleotide Structure • 5’ refers to the #5 carbon in the deoxyribose sugar. • 3’ refers to the #3 carbon in the deoxyribose sugar.

  14. Double Helix Structure • Complementary strands are ANTI-PARALLEL; bonded in OPPOSITE directions. • One side is 5’ to 3’, the other is 3’ to 5’.

  15. Section 10.2 • Chain elongation occurs in the 5' to 3' direction by addition of one nucleotide at a time to the 3' end (Figure 10.8). • As the nucleotide is added, the two terminal phosphates are cleaved off.

  16. Section 10.2 • DNA polymerases I, II, and III can elongate an existing DNA strand (called a primer) but cannot initiate DNA synthesis (Table 10.2). • All three possess 3' to 5' exonuclease activity. • But only DNA polymerase I demonstrates 5' to 3' exonuclease activity.

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