polynucleotides and DNA

• Nucleotides join together to form polynucleotides
• 1. nucleotides join up between the phosphate group of one nucleotide and the sugar of another via condensation reaction. forms a phosphodiester bond
  2. the chain of sugars and phosphates is the sugar-phosphate backbone
  3. can be broken down into nucleotides again by breaking phosphodiester bonds using hydrolysis
• 2 polynucleotide strands join to form a double helix
• • 2 DNA strands join together by hydrogen bonding between the bases.
  • each base can only pair with a set partner - complementary base pairing
  • (A-T) 2 hydrogen bonds
  • (G-C) 3 hydrogen bonds
  • antiparallel
• label the diagram

  A) 3 hydrogen bonds

  B) antiparallel

  C) 2 hydrogen bonds

  D) c

  E) g

  F) a

  G) t