nucleic acids

• DNA made up of nucleotides
• Mononucleotide 


  = phosphate group, pentose sugar, nitrogenous bases

  • 2 condensation reactions

  
• pentose sugar 


  -DNA= deoxyribose

  -RNA= ribose

  • phosphodiester bond

  
• nitrogenous base


  DNA= thymine, adenine, cytosine, guanine

  RNA= adenine, cytosine, guanine, uracil

  • hydrogen bonds form between the bases (A,T= 2bonds C,G=3 bonds)
  • purines= larger bases, contain a double carbon ring structure A,G
  • pyrimidines= smaller bases, contain single carbon structures T,C,U
• the genetic code 


  -Triplet code= a combination of 3 bases, codes for 1 amino acid

  • codon= 3-base sequence of DNA or RNA
  • gene= section of DNA, contains sequence of bases to code for a polypeptide.
  • universal= all organisms use the same code
  • non-overlapping= each base is only read as part of one codon
  • degenerate= more than 1 codon for each amino acid and stop codons too.
• extracting DNA

  1. grind sample in a mortar and pestle- breaks down cell wall.
  2. mix sample with detergent- breaks down cell membrane.
  3. add salt- breaks hydrogen bonds between DNA and water molecules.
  4. add protease enzymes- break down proteins associated with DNA.
  5. add layer of ethanol on top of sample- causes the DNA to precipitate out of solution.
  6. DNA will be seen as white strands forming the layer of sample and layer of alcohol. DNA can be picked up by 'spooling' in onto a glass rod.