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Gene Technology – Revision Pack (B6) Principles of Genetic Engineering: The process of genetic engineering involves transferring a gene from one organism to another. The organism which receives the new gene is known as a transgenic organism. There are a number of steps taken in genetic engineering: STEP 1 – the desired characteristic is identified and removed STEP 2 – DNA from another organism is cut open STEP 3 – the new gene is inserted into the DNA To cut and insert the DNA enzymes are used. STEP 4 – you must check that the gene works in the transgenic organism Transgenic organisms can often be cloned to produce identical copies. The above example uses bacteria which produce asexually. The process of genetic engineering ONLY works because the genetic code is universal. This means that the genes from one organism will produce the same protein in another organism. Restriction enzymes are used to cut open the DNA. They leave several unpaired bases (single strands) on the cut end. This acts as a ‘sticky end’. Ligase enzymes will join DNA strands because the ‘sticky’ ends on each cut section of DNA can join by complementary base pairing (A-T, C-G). Genetic Engineering Bacteria: Bacteria can be used in genetic engineering to produce human insulin; this happens via the following steps: STEP 1 – cut the gene for producing human insulin out of human DNA STEP 2 – cut open a loop of bacterial DNA Gene Technology – Revision Pack (B6) STEP 3 – insert the insulin gene into the loop STEP 4 – insert the loop into the bacterium Many copies of the bacteria are cultured by cloning and large quantities of insulin are made. The loops of DNA used are called plasmids. These are found in the cytoplasm of the bacteria and due to the fact that they are taken up from bacteria means they can be used as vectors for genes. Not all of the bacteria will take up a plasmid, so to work out which ones have/haven’t, scientists use an assaying technique: STEP 1 – scientists add genes that make the bacteria resistant to antibiotics STEP 2 – the bacteria are then grown on an agar containing the antibiotic STEP 3 – scientists ONLY choose the bacteria that survive (that are resistant to the antibiotic) because they have taken up the antibiotic plasmid, and will have taken up the insulin plasmid DNA Fingerprints: DNA ‘fingerprints’ can be produced to identify individuals. They can be stored to identify people who commit crimes and prove the innocence of others. However, some people disagree with storing this information because it could be used to assess the possibility of someone getting a life-limiting disease – this could be used as a reason to withhold life insurance. To produce a DNA ‘fingerprint’, the following steps are used: STEP 1 – DNA is extracted from a sample (e.g. blood) STEP 2 – the DNA is cut up or fragmented using restriction enzymes STEP 3 – the fragments are separated using electrophoresis STEP 4 – the fragments are then made visible using a radioactive probe In the image above, you can clearly see that suspect two was present at the crime scene, and it is this sort of information which is used by police detectives and forensic examiners to prove guilt (suspect 2) and innocence (suspects 1 and 3). Gene Technology – Revision Pack (B6) Past Papers: PPQ(1): PPQ(2): Gene Technology – Revision Pack (B6) PPQ(3): Gene Technology – Revision Pack (B6) PPQ(4): Continued on next page... Gene Technology – Revision Pack (B6) Gene Technology – Revision Pack (B6) Mark Schemes: PPQ(1): PPQ(2): PPQ(3): PPQ(4):