Bio3400 Chapter 11 DNA Replication and Recombination
  1. The                  of DNA strands allows each strand to serve as a           for synthesis of the other.

  2. DNA replication in bacteria begins at the         of replication and is                .

    • The DNA helix is unwound by proteins called            which bind to the origin of replication and break the           bonds between the bases.

    • Producing of DNA polymers requires a      primer made by the enzyme          .

    • Polymerization is catalyzed by several DNA polymerases.

    • Chain             occurs in the 5' to 3' direction by addition of one nucleotide at a time to the 3' end.

    • DNA synthesis is continuous along the          strand of the replication fork, but is discontinuous along the          strand. Synthesis is             on both strands.

    • The RNA primer is removed by                   which replaces it with DNA bases.

    • The Okazaki fragments are joined together by DNA         , which forms the missing phosphodiester bonds between the fragments.
    Prokaryote DNA synthesis summary.

  3. Eukaryotic DNA synthesis is more complex than that in prokaryotes.
    • Eukaryotic genomes are         and contain multiple origins of replication to allow the genome to be replicated in a few hours.

      • Several DNA              have been discovered; four partake in replication, the rest are involved in         processes.

    • Eukaryotic chromosomes are complexed with           , forming              that also need to be duplicated during DNA synthesis.

    • Eukaryotic chromosomes are         rather than circular, and pose a problem when terminating replication on the          strand.

      • Repeating sequences of DNA called            are synthesized by the enzyme             to prevent chromosome shortening in       cells.

    • Homologous                in general involves DNA exchange along two chromosomes with sequence homology.

    • DNA recombination can also occur by gene             , caused by excision repair of a heteroduplex in meiosis.