3.3 dna structure

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3.3 dna structure

  1. 1. 3.3 DNA Structure Topic 3 The Chemistry of Life
  2. 2. 3.3.1 Outline DNA nucleotide structure in terms of sugar (deoxyribose), base and phosphate. (Chemical formulas are not required. Simple shapes can be used to represent the component parts. Only the relative positions are required) 3.3.2 State the names of the four bases in DNA. 3.3.3 Outline how DNA nucleotides are linked together by covalent bonds into a single strand. (Only the relative positions are required) DNA Structure
  3. 3. DNA Structure 3.3.4 Explain how a DNA double helix is formed using complementary base pairing and hydrogen bonds. 3.3.5 Draw and label a simple diagram of the molecular structure of DNA. A diagram showing the complementary base pairs of A–T and G–C, held together by hydrogen bonds and the sugar–phosphate backbones is sufficient. The number of hydrogen bonds between pairs and details of purine or pyrimidines are not required.
  4. 4. DNA is Made of Nucleotides DNA (Deoxyribose Nucleic Acid) is a macro molecule made up of smaller sub units called Nucleotides. Each nucleotide consists of : – a nitrogenous base (Adenine, Thymine, Cytosine, Guanine) – a deoxyribose sugar (a pentose sugar) – a phosphate group
  5. 5. Nitrogenous Bases In DNA there are four nitrogenous bases. They exhibit complementary base pairing whereby: – Adenine always joins with Thymine. – Guanine always joins with Cytosine. This is due to the length of the bases and the number of hydrogen bonding sites.
  6. 6. DNA Structure DNA is formed from long chains of Nucleotides. The structure of DNA is similar to a twisted ladder. The rungs of the ladder are made from the complementary bases. The sides of the ladder are made from alternate sugar and phosphate groups.
  7. 7. DNA Structure
  8. 8. 3.3.1 Outline DNA nucleotide structure in terms of sugar (deoxyribose), base and phosphate. (Chemical formulas are not required. Simple shapes can be used to represent the component parts. Only the relative positions are required) 3.3.2 State the names of the four bases in DNA. 3.3.3 Outline how DNA nucleotides are linked together by covalent bonds into a single strand. (Only the relative positions are required) IBO guide:
  9. 9. IBO guide: 3.3.4 Explain how a DNA double helix is formed using complementary base pairing and hydrogen bonds. 3.3.5 Draw and label a simple diagram of the molecular structure of DNA. A diagram showing the complementary base pairs of A–T and G–C, held together by hydrogen bonds and the sugar–phosphate backbones is sufficient. The number of hydrogen bonds between pairs and details of purine or pyrimidines are not required.

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