DNA STRUCTURE BIO

• DNA


  Double helix or twisted ladder
• The double helix structure of DNA was proposed by James Watson and Francis Crick in 1953 and is widely accepted today as correct
• DNA


  Deoxyribonucleic acid
• DNA


  • Composed of smaller units (monomers) called nucleotides
  • Each nucleotide contains a sugar called deoxyribose, a phosphate group, and one of four different nitrogenous bases
• Nitrogenous bases in DNA

  • Adenine (A)
  • Thymine (T)
  • Guanine (G)
  • Cytosine (C)
• Purines


  Larger nitrogenous bases (adenine and guanine)
• Pyrimidines


  Smaller nitrogenous bases (thymine and cytosine)
• Structure of DNA molecule

  1. Two strands of nucleotides lined up next to each other

  2. Deoxyribose sugars and phosphate groups form the "backbone"

  3. Base pairs form the "rungs"
• Base pairing rules


  Adenine always matches with thymine, guanine always matches with cytosine
• Hydrogen bonds


  Weak bonds that hold the base pairs together
• Watson, Crick and Maurice Wilkins received the Nobel Prize in physiology and medicine for discovering the structure of DNA
• Watson and Crick realized the DNA structure lends itself well to self-replication so the cell can easily make exact copies of its own DNA