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Unit 3: Genetics The Molecular Basis of Inheritance Review
  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.
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