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  1. 1. 13.2 DNA Structure What does DNA stand for? Deoxyribonucleic acid
  2. 2. DNAs Functions: <ul><li>Controls the production of proteins </li></ul><ul><li>Can copy itself for new cells </li></ul><ul><li>Carries genetic information from one generation to the next </li></ul>
  3. 3. replication transcription processing translation
  4. 4. II. Structure of DNA <ul><li>Monomer of DNA= nucleotide </li></ul><ul><li>DNA is made of 2 chains of nucleotides. </li></ul><ul><li>3 parts of a nucleotide: </li></ul><ul><ul><li>Pentose (5C) sugar = deoxyribose </li></ul></ul><ul><ul><li>Phosphate group </li></ul></ul><ul><ul><li>Nitrogen base </li></ul></ul>
  5. 6. Bases in DNA purines pyrimidines adenine guanine cytosine thymine N9 N1
  6. 7. <ul><li>The nucleotides are joined in a chain; each nucleotide joined to the next by a covalent bond between the sugar and phosphate. </li></ul><ul><li>Therefore the DNA molecule has a direction to it. </li></ul>
  7. 8. <ul><li>Due to Rosalind Franklin’s x-ray diffraction work, Watson and Crick knew that DNA was a helix. </li></ul>
  8. 9. <ul><li>Watson and Crick realized in 1953 that the DNA molecule is composed of two strands running in opposite directions= antiparallel </li></ul>
  9. 12. Double helix <ul><li>The two strands are linked in the center by hydrogen bonds. </li></ul>
  10. 13. “ Chargaff’s rules” <ul><li>1950 </li></ul><ul><li>Determined that the amount of: </li></ul><ul><ul><li>Adenine=Thymine </li></ul></ul><ul><ul><li>Cytosine=Guanine </li></ul></ul><ul><ul><li>in DNA. </li></ul></ul>
  11. 14. <ul><li>Watson and Crick deduced that A must pair with T and G with C </li></ul><ul><li>=complimentary pairs </li></ul>
  12. 17. What about the structure of DNA varies from one individual to the next? The sequence of nitrogen bases