1.5 Biotechnology 1.

• Cutting Out the Gene- Restriction Enzymes

  1. Restriction enzymes cut the sugar-phosphate backbone at specific locations leaving ‘sticky ends’ to allow the DNA to be inserted into other DNA samples

  2. DNA cut by restriction enzymes are often inserted into bacterial plasmids
• Use of DNA information for things like insurance etc discrimination
• Uses Of DNA Fingerprinting/ Profiling

  • Forensics- identifying criminals using DNA found at crime scenes
  • Identifying where poached animals have come from
  • Paternity- identify the parents- specifically the father of the children
  • Genome mapping species- looking at evolution and speciation
  • Understanding heredity and ancestry
  • Medical testing and personalized diets
• Amplifying DNA- Polymerase Chain Reaction (PCR)


  1. Taking a small amount of DNA and making copies (like DNA replication, but ‘on demand’

  2. Steps: DNA is heated to around 95 degrees to separate the strands

  3. Primers (short DNA/RNA strands) are added and the mix is cooled to around 55 degrees

  4. Primers attach to the DNA strand, preventing them from joining back together, they also provide a strong point for DNA replication

  5. The solution is reheated to 72 degrees and free nucleotides are added, along with DNA polymerase which joins the free nucleotides with the original DNA strand

  6. This process is repeated to copy the original DNA strand

  7. One PCR cycle takes 5 minutes, 30 cycles can provide 71 billion copies

  8. PCR has been a major breakthrough in biotechnology and has enabled many advancements in bioscience
• There are now laws against the use of genetics info for such things
• DNA Extraction

  1. Cell membrane is broken, releasing cell content

  2. Enzymes are used to remove proteins and histones to ‘unwind’ DNA

  3. DNA is then isolated, amplified and analyzed
• Issues
• Information bias- most of our genetic testing comes from European DNA= information bias that could cause gaps in knowledge and treatments
• DNA Technique- Electrophoresis


  1. DNA is obtained and amplified using PCR, it is then cut using restriction enzymes

  2. DNA samples are placed in a gel plate at the negative end (the plate has positive and negatively charged ends)

  3. An electric current is passed through the gel, DNA is negatively charged, so it starts to move towards the positive side of the plate, through the gel

  4. Shorter fragments of DNA can move faster and further through the gel

  5. After a set time, the current is switched off and an electropherogram is developed showing each separated DNA strand and its length

  6. The location and length of each DNA strand is unique for each individual- therefore producing a DNA fingerprint

  7. This can be compared between individuals for different purposes
• Locating Genes- Gene Probes

  1. A probe is a single strand of DNA or mRNA with a complementary sequence to the desired gene; it also contains radioactive or fluorescent labels

  2. Heat is used to separate sample DNA strands before adding the probe

  3. The probe pairs with the complementary bases on the gene of interest, highlighting the gene and allowing it to be located easily