1. 3.5 GENETIC MODIFICATION AND BIOTECHNOLOGY

2. UNDERSTANDING Gel electrophoresis is used to separate proteins of fragments of DNA according to size PCR can be used to amplify small amounts of DNA DNA profiling involves comparison of DNA Genetic modification is carried out by gene transfer between species Clones are groups of genetically identical organisms, derived from a single original parent cell Many plant species and some animal species have natural methods of cloning Animals can be cloned at the embryo stage by breaking up the embryo into more than one group of cells Methods have been developed for cloning animals using differentiated cells

3. DNA PROFILING (DNA FINGERPRINTING) Uses: To determine guilt or innocence of crime suspects To determine paternity To determine family relations

4. HOW DOES IT WORK 1.A sample of DNA is obtained 2.Sequences of DNA that vary between individuals are selected for analysis. These are called Restriction Fragment Length Polymorphisms or RFLPs ) 3.RFLPs are combined with restriction enzymes endonucleases (also called restriction enzymes) 4.Restriction enzymes cut DNA where they have specific base sequences For example, EcoRI searches the sequence of DNA bases and cleaves DNA at the following location between G and A 5' - GAATTC - 3' 3' - CTTAAG - 5'

5. HOW IT WORKS ( DNA FINGERPRINTING) 5.Once the DNA has been digested it is placed in a chamber. 6.This chamber contains a gel that the DNA can travel through. It is called an electrophoresis gel. 7.An electrical current is applied to the chamber and DNA is pulled towards the positive end (because DNA is negative) 8.Smaller fragments of DNA travel more quickly through the gel while larger fragments move more slowly

6. DNA FINGERPRINTING (GEL ELECTROPHORESIS) DNA is treated with a fluorescent chemical to make it more visible Each person’s DNA will leave a unique banding pattern on the gel Samples of different DNA can be compared to determine guilt or innocence

7. GENE TRANSFER TO BACTERIA Bacteria provide an excellent vehicle for cloning a gene or producing its protein For this reason, biologists often transfer genes into bacteria Example 1 A protein, when present in plants, makes them unappetizing to insects. Scientists want to insert this gene into all crops to make them resistant to insects Example 2 Scientists have isolated the gene for human growth hormone. They want to use the gene to make large amounts of the hormone to give to children whose growth is stunted

8. GENE TRANSFER To get a gene into a bacteria the following steps are followed: 1.DNA is isolated and the desired gene is removed using restriction enzymes 2.The gene is inserted into a special genetically engineered plasmid. The plasmid is opened using the same restriction enzyme so the gene fits tightly into it 3.DNA Ligase is used to connect the gene to the plasmid

9. GENE TRANSFER This plasmid has been created by biologists and has several important features. It has several sites where restriction enzymes can cut it It also has several genes that make it resistant to certain antibiotics

10. GENE TRANSFER 4.A bacteria is treated with calcium chloride and given a mild electrical current. This makes its membrane more permeable so a plasmid can enter inside it. A process known as transformation. It doesn’t always work. Some plasmids get in, others do not. 5.Bacteria are treated with antibiotics. This is done so bacteria without plasmids will be killed. Remember, the plasmid has a gene that makes it resistant to antibiotics and we only want bacteria with plasmids in them.

11. GENE TRANSFER The remaining bacteria a placed in a medium that allows them to quickly multiply and produce billions of copies of the original gene and/or the protein that the gene codes for.

12. GENE CLONING/TRANSFER