Dna strycture 2

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Dna strycture 2

  1. 1. DNA THE ALPHABET OF LIFE
  2. 2. Stores and passes on genetic information from one generation to another. DNA DEOXYRIBONUCLEIC ACID
  3. 3. DNA STRUCTURE THE DNA STRUCTURE IS SHAPED LIKED A SPIRAL STAIRCASE, OR TWISTED LADDER.
  4. 4. DNA STRUCTURE (An Overview) <ul><li>DNA has three main components: </li></ul><ul><li>Deoxyribose ( pentose sugar) </li></ul><ul><li>Base (there are four different ones) </li></ul><ul><li>Phosphate group </li></ul>
  5. 5. The deoxyribose sugar of the DNA backbone has 5 carbons and 3 oxygens. DNA STRUCTURE
  6. 6. DNA STRUCTURE THE STEPS OF THE LADDER ARE MADE OF PAIRS OF NITROGEN BASES.
  7. 7. DNA STRUCTURE <ul><li>They are divided into two groups </li></ul><ul><ul><li>Pyrimidines and purines </li></ul></ul><ul><li>Pyrimidines (made up of 6 atoms 4 carbon 2 nitrogen rings) </li></ul><ul><ul><li>Thymine </li></ul></ul><ul><ul><li>Cytosine </li></ul></ul><ul><li>Purines (larger of the two bases; made up of 9 atoms that make up the fused rings 5 carbon, 4 nitrogen ) </li></ul><ul><ul><li>Adenine </li></ul></ul><ul><ul><li>Guanine </li></ul></ul>
  8. 8. DNA STRUCTURE <ul><li>ADENINE = A </li></ul><ul><li>GUANINE = G </li></ul><ul><li>CYTOSINE = C </li></ul><ul><li>THYMINE = T </li></ul><ul><li>They are represented by their capital letter. </li></ul>
  9. 9. DNA STRUCTURE There is only one way the nitrogen bases can form ADENINE pairs with THYMINE GUANINE pairs with CYTOSINE
  10. 10. DNA STRUCTURE QUESTION ? CAN C JOIN WITH A AND G JOIN WITH T YES NO
  11. 11. CORRECT MOVE ON
  12. 12. SORRY REVIEW MORE
  13. 13. DNA STRUCTURE Nucleotides Nucleotides are formed by the condensation of a pentose sugar, phosphate and one of the 4 bases The following illustration represents one nucleotide CIRCLE = Phosphate PENTAGON= Deoxyribose Rectangle= Base
  14. 14. DNA STRUCTURE DNA Double Helix and Hydrogen Bonding <ul><li>Made of two strands of nucleotides that are joined together by hydrogen bonding </li></ul><ul><li>Hydrogen bonding occurs as a result of complimentary base pairing </li></ul><ul><ul><li>Adenine and thymine pair up </li></ul></ul><ul><ul><li>Cytosine and guanine pair up </li></ul></ul><ul><ul><li>Each pair is connected through hydrogen bonding </li></ul></ul><ul><ul><li>Hydrogen bonding always occurs between one pyrimidine and one purine </li></ul></ul>
  15. 15. DNA STRUCTURE <ul><li>Adenine always pairs with thymine because they form two H bonds with each other </li></ul><ul><li>Cytosine always pairs with guanine because they form three hydrogen bonds with each other </li></ul>
  16. 16. DNA STRUCTURE Antiparallel strands The strands run opposite of each other. The 5’ end always has the phosphate attached. ’
  17. 17. SAMPLE QUESTION Which of the following nucleotide base sequences complements the section of DNA modeled above? F. 5′UTCGCA3′ G. 5′TTAGCG3′ H. 5′GCGATT3′ J. 5′TTUCGC3′ 3′AATCGC 5′
  18. 18. SAMPLE QUESTION The Correct Answer: G G is the right answer because A (adenine) always pairs with T (thymine) and C (cytosine) always pair with (guanine).

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