DNA

• DNA can be replicated with high fidelity for daughter cells
• DNA is a large polymer of nucleotides
• nucleotide components

  phosphate, deoxyribose sugar, and base
• purine nucleotides

  guanine and adenine
• pyrimidine nucleotides

  thymine and cytosine
• how are nucleotides joined

  covalent phosphodiester bond between 5' carbon and 3' carbon
• 5'


  start of DNA strand
• 3'


  where next free nucleotide joins
• Chargaffs rule

  total purines = total pyrimidines
• how are DNA strands held together

  hydrogen bonding in opposite directions
• A and T

  2 hydrogen bond
• C and G

  3 hydrogen bonds
• why is binding reversible

  strands need to seperate for replication and transcription
• start codon

  ATG
• stop codons

  TAA, TAG, TGA
• nucleotide substitution

  missense mutation
• nucleotide substitution with no change

  silent mutation
• deletion or insertion

  frame shift mutation
• stop codon introduced mutation

  non-sense mutation
• there is a small amount of DNA in the mitochondria