DNA

• These are the Purines. They are larger and contain double carbon ring structures

  (pure as gold = purines, adenine, guanine)

  
• These are the Pyrimidines. These are smaller and contain single carbon ring structures.

  
• Pyrimidines bond to Purines -

  Adenine to Thymine

  Cytosine to Guanine

  
• • There are 3 bonds between C and G
  • There are 2 bonds between A and T
• The two strands of the double helix are held together by the hydrogen bonds between base pairs.

  The strands are antiparallel (one goes 5’ to 3’ and the other goes the other way)

  
• DNA extraction -

  1. grind the sample with a mortar and pestle
  2. mix the sample with detergent
  3. add salt
  4. filter the mixture
  5. add protease enzyme
  6. add ethanol on top of the sample
  7. DNA will form in white strands
• filtering - removes any debris (big, insoluble bits of cell) from the mixture
• detergent - This breaks down the cell membrane and releases cell contents into solution
• salt - Breaks hydrogen bond between DNA and water molecules
• ethanol - This causes the DNA to precipitate (i.e. to come out of solution) as DNA is not soluble in cold alcohol
• protease - Breaks down proteins associated with DNA in the nuclei
• grind sample - Breaks down the cell walls