Bio1151b Chapter 16 The Molecular Basis of Inheritance
  1. The physical structure of nucleic acids such as RNA or      was discovered by Watson and Crick from photos of        crystallography made by Rosalind Franklin.
  2. DNA is a double        , with the sugar-phosphate backbones on the outside, and complementary pairs of              bases on the inside.
  3. Weak           bonds form between the base pairs:          (A) always pairs with          (T), and           (C) always pairs with          (G). Summary.
  4. The base-pairing rules are used for DNA              : each strand acts as a           for building a                strand in a                   process.
  5. The replication occurs in three phases:             ,             , and              .
    • Initiation begins at          of replication, where the two strands are unwound by           . The enzyme          adds a sequence of RNA         nucleotides at the replication        .
    • Polymerization always proceeds 5' to 3'. There is a          strand of continuous synthesis, and a          strand where synthesis occurs in          fragments.
    • Elongation is the addition of more              to the         , catalyzed by DNA polymerase III.
    • Termination occurs when                   replaces the primer with DNA nucleotides, and DNA         joins together the fragments to complete the new strand. Summary.
  6. Base-pairing is about 99.999% accurate, an error occurs about 1 in          base pairs. DNA              can "proofread" during polymerization and replace most incorrect nucleotides.
  7. Uncorrected or damaged DNA can be repaired by         enzymes. The overall error rate is about 1 in             nucleotides, or 99.99999999% accurate.