biotechnology

• DNA can be processed by:

  • making copies of sample using polymerase chain reaction (PCR)
  • cutting DNA into smaller lengths via restriction enzymes
  • separating DNA lengths via gel electrophoresis to produce a DNA profile
  • determining the sequence of nucleotides or their bases using Sanger’s method
• Polymerase chain reaction:

  • enabled small number of DNA to be replicated → testable amounts produced to use in analysis techniques
  • mimics natural process of DNA replication occurring prior to cell division
  • involves the steps of denaturing, annealing and extension
• Denaturation:

  • enzyme helicase separates the two DNA strands
  • PCR uses heat to achieve same function
  • 94-96 degrees heat are used to break the hydrogen bonds
• Annealing:

  • temperature decreased to 50-60 degrees
  • primers (short DNA strands) will bind to the single DNA strands
• Extension: (elongation)

  • DNA polymerase used to join new, complementary nucleotides to sections originating with the primers
  • heat-stable DNA polymerase used to minimise number of enzymes used
  • phase carried out at Taq polymerase’s optimmal temperature of 68-72 degrees
• Gel electrophoresis:

  • technique that separates DNA strands based on their lengths
  • banding pattern created is an individual’s DNA profile
  • DNA ladder used to determine the length of the DNA strands
  • ethidium bromide (carcinogen)
  • used to make DNA visible under UV light
• DNA sequencing:

  (placing ‘ingredients’ to create a new DNA strand into a vessel to determine the specific base sequence of DNA)

  • when DNA forms:
  • each nucleotide loses two phosphate groups
  • sugar molecule loses a hydrogen atom from the hydroxy group when bonding to phosphate group
• Ethical consideration with genetic information:

  • autonomy - respect for the right to be self-determining
  • confidentiality - genetic information is treated sensitively
  • equity - right to fair and equal treatment regardless
  • privacy - right to make decisions alone
• comparative genomics - comparison of genome sequences of different species as all organisms use the same DNA code
• Endogenous retroviruses: (ERVs)

  (’non-functional ‘DNA that is a viral sequence, their genetic information is stored as RNA)

  • retrovirus copies its RNA genome into DNA via reverse transcription
  • DNA inserted into one of the host cell’s chromosomes
  • only becomes endogenous if the chromosome its inserted in gamete
  • all subsequent generations will have copy of ERV at same location
• mtDNA:

  • only inherited from egg
  • higher mutation rate than nuclear DNA
  • amount of mutation is roughly proportional to the amount of time passed
• Protein sequences:

  • comparison of type and sequence of amino acids in similar proteins allows the degree of similarity to be establishment
  • animals of the same species have identical amino acid sequences in their proteins
  • different species have either different amino acids or are arranged in a different order
  • degree of difference allows an estimate of the amount of evolution take place