Structure of DNA and RNA

Structure of DNA and RNA

1. Nucleic acids and nucleotides

   • nucleic acids DNA and RNA polymers of nucleotides
   • first discovered in materials extracted for cell nuclei
   • Nucleic acids = large molecules made by linking nucleotides to form polymer
   • parts of a nucleotide
     • pentose sugar; 5 C atoms
     • phosphate group; negatively charged; acidic
     • base; contains N; 1 or 2 rings of atoms
   • base and phosphate group linked to sugar by covalent bonds
   • strong backbone; sugar phosphate structure
   • 4 diff bases = 4 diff nucleotides
   • any base sequence possible; stores genetic info

2. Differences between DNA and RNA

   • number of strands present
     • DNA = 2
     • RNA = 1
   • base composition
     • DNA = adenine, cytosine, guanine, thymine
     • RNA = uracil instead of thymine
   • type of pentose
     • DNA = deoxyribose
     • RNA = ribose

3. Structure of DNA

   • strands wound; double helix
   • antiparallel (opposite) strands of nucleotides
   • linked by hydrogen bond b/ween complementary pars
   • each strand, chain of nucleotides; covalent bond
   • complementary base pairing

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