NOTES: Genetic engineering

1. NOTES: Genetic engineering Unit 7 – Genetic Technology & Ethics Chapters 13 & 14

2. What is Genetic Engineering? • GeneticEngineering (GE) is the modification of an organism’s genetic composition by artificial means • It involves using restriction enzymes to transfer DNA from one organism to another to give the recipient new traits • The result is called recombinant DNA, as it contains DNA from two different individuals that have been “recombined” into a single genome • Transgenic or GeneticallyModified Organisms (GMOs) are organisms that contain genes from two or more organisms

3. Why Are Bacteria Used Often in GE? • Bacteria are often used as subjects in genetic engineering because.... • They are unicellular, so it is pretty easy to get the recombinant DNAback into the cell after it’s been changed • They reproduce quickly and asexually (meaning all daughter cells will contain identical DNA as parent cell) • Bacteria contain plasmids: small circular pieces of extra DNA that can easily take in new genes

4. Bacterial Plasmids Plasmids … -are small circles of DNA -replicate independently of the bacterial chromosome -work well for DNA transfer, as pieces of foreign DNA can be added to them -replication often produces 50-100 copies of a recombinant plasmid in each cell!

5. How Do You Genetically Engineer? • The process of genetically engineering a bacterium is relatively simple. • The 4 steps are: • Isolate DNA • Genetic Recombination • Genetic Transformation • Mass Production of Proteins

6. GE STEP 1: Extract DNA • Locate the gene(s)ofinterest in the subject’s genome (the HGP has worked on “mapping” where human genes are located) • This gene codes for the protein that gives the trait you are trying to study or add to another organism • Examples: Gene for producing insulin from humans; gene for antibioticresistance from bacteria; gene for growth hormone from livestock animals • Extractthegeneofinterest from the host DNA (usually done by using restriction enzymes) • Extractthebacterial (plasmid) DNA from the bacterial sample (usually done by exploding the cell with heat)

7. Step #1 Extract human DNA containing the gene of interest and the bacterial plasmid

8. GE STEP 2: Genetic Recombination • Cut the subject’s DNA and bacterial plasmid DNA with the SAME restriction enzyme to produce complementary sticky ends • Mix the fragment of DNA containing the gene of interest with the bacterial plasmid so the complementary sticky ends combine due to hydrogenbondingforces. • DNAligase joins the fragments together, creating one plasmid containing genetic information from two (or more) different organisms. This is now called recombinant DNA.

10. Step #2 Cut subject DNA containing gene of interest and bacterial plasmid with the SAME restriction enzyme. This will produce complementary sticky ends so that DNA ligase will “glue” the pieces together

11. GE STEP 3: Genetic Transformation • Reinsert the new recombinant DNA plasmid back into the bacterial cell in a process called genetic transformation. • A process known as heat shock works well for bacterial transformation – when the bacteria is heated up suddenly, a pressure difference between the inside and outside of the cell is created. This allows the recombinant plasmid to get “pushed” into the bacterial cell easily. • Electric shock is used to transform animal cells. • If transformation was successful, you now have a transgenic or genetically modified organism

12. Step #3 Put recombinant DNA back into the bacterial cell (transformation) via heat shock. You now have a GMO!

13. GE STEP 4: Mass Produce Proteins • Provide the bacteria with the conditions necessary for growth (nutrients, moisture, and temperature). They will begin reproducing via the process of mitosis, producing identical copies of themselves exponentially. • Watch your transformed bacterial cells produce MASS quantities of the protein of interest (like a factory)! • Bacteria can be filtered out after they have made the protein, and that protein can be packaged for medicinal purposes or studied in the lab

14. Step #4 Transgenic bacteria will now reproduce asexually (mitosis), making identical transgenic clones. Each bacterial cell will now produce desired protein!