Genetics Ch. 10

• DNA

  Molecules responsible for the instructions for life
• Molecules responsible for heritability

  • Be able to store complex information
  • Replicate faithfully
  • Encode phenotype
  • Allow for variability between individuals
• DNA

  Polymer made of nucleotides (monomers)
• DNA bases

  • Adenine (A)
  • Thymine (T)
  • Guanine (G)
  • Cytosine (C)
• Tetranucleotide theory was wrong
• Chargaff's rules

  • Distribution of the bases varies from species to species
  • A=T and G=C
• Wilkins and Franklin used X-ray crystallography to elucidate the structure of DNA
• Watson and Crick came up with the model for the structure of DNA based in part on Levene, Chargaff's rules, and Franklin and Wilkins' DNA structure
• Wilkins, Watson and Crick won the Nobel Prize in 1962
• Primary structure of DNA

  Nucleotide sequence
• Nucleotide

  Contains phosphate, ribose sugar, and nitrogenous base
• Nucleoside

  Lacks the phosphate
• DNA secondary structure

  • Antiparallel strands
  • Bases are hydrogen bonded to each other (complementary base pairing)
  • Sugars and phosphates are on the outside
• RNA secondary structure

  • Single strand, meaning it can interact with itself to form a structure
  • Base pairing can exist between bases on the same strand, hairpin structure; same strand folding upon itself
• Deoxyribose


  lacks oxygen unlike Ribose
• Purine

  Double Ring; Adenine (A) and Guanine (G)
• Pyrimidine

  Single Ring; Cytosine (C), Thymine (T), and Uracil (U)
• RNA molecules may contain numerous hairpins, allowing them to fold up into complex structures
• H-DNA

  three-stranded (triplex); long sequences of only purines or only pyrimidines; break more often and common in mammals