the genome

• what is DNA ?


  • A double stranded polymer of nucleotides
  • forms a double helix
• what are the monomers of DNA ? (monomers - atoms or small molecules that bond together to form more complex structures)


  nucleotides
• What are DNA nucleotides made of ?

  • common sugar
  • phosphate group
  • one of the 4 bases : A, T, C, G
• what are the 4 bases found in the nucleotides names

  Adenine, Thymine, Cystonine and Guanine
• how do nucleotides subtract to form molecules of DNA ?


  • SUGAR and PHOSPHATE molecules join to form a sugar-phosphate backbone in each strand of DNA
  • bases are connected to the sugars
  • complementary base pairs are joined by a weak bond of hydrogen (A - T and C - G)
• genome :


  entire genetic material of an organism
• chromosome 


  long, coiled molecule of DNA which carries genetic information in form of genes
• gene


  section of DNA which codes for a specific sequence of amino acids which form a protein by polymerisation
• how to extract DNA from a fruit ?


  1. place piece of fruit in a plastic bag or beaker and crush it thoroughly
  2. add detergent and salt to the mix
  3. filter the mixture using filter paper and collect any large bits of the fruit in the filter
  4. poor chilled ethanol into a test tube
  5. DNA precipitates forming fibrous white solid
  6. use a glass rod to collect the DNA sample out of the test tube
• detergent is added to the crushed fruit because it disrupts the cell membranes which gets the DNA to release into the solution
• salt added to crushed fruit as it encourages the DNA to precipitate
• chilled ethanol added instead of water because it's insoluble and encourages precipitation
• how does gene code for a protein ?


  • sequence of 3 bases in a gene form a triplet
  • each triplet codes for a single amino acid
  • the order of the amino acid determines the structure (how it'll fold) and function of the protein is formed
• folding of amino acids in proteins such as enzymes because it determines the shape of the active site which must be highly specific to the shape of the substrate to fit
• what is protein synthesis ?


  formation of protein from a gene
• two stages of protein synthesis :


  • transcription
  • translation
• transcription - formation of mRNA from DNA template