1. Explain how scientists manipulate DNA. Describe the importance of recombinant DNA. Define transgenic and describe the usefulness of some transgenic organisms to humans.

2. Lesson Summary Copying DNA Genetic engineers can transfer a gene from one organism to another to achieve a goal, but first, individual genes must be identified and separated from DNA. The original method (used by Douglas Prasher) involved several steps: 1. Determine the amino acid sequence in a protein. 2. Predict the mRNA code for that sequence. 3. Use a complementary base sequence to attract the predicted mRNA. 4. Find the DNA fragment that binds to the mRNA. Once scientists find a gene, they can use a technique called the polymerase chain reaction to make many copies. 1. Heat separates the DNA into two strands. 2. As the DNA cools, primers are added to opposite ends of the strands. 3. DNA polymerase adds nucleotides between the primers, producing two complementary strands. The process can be repeated as many times as needed.

3. Lesson Overview Lesson Overview Recombinant DNA Polymerase Chain Reaction Once biologists find a gene, a technique known as polymerase chain reaction (PCR) allows them to make many copies of it. 1. A piece of DNA is heated, which separates its two strands.

4. Lesson Overview Lesson Overview Recombinant DNA Polymerase Chain Reaction 2. At each end of the original piece of DNA, a biologist adds a short piece of DNA that complements a portion of the sequence. These short pieces are known as primers because they prepare, or prime, a place for DNA polymerase to start working.

5. Lesson Overview Lesson Overview Recombinant DNA Polymerase Chain Reaction 3. DNA polymerase copies the region between the primers. These copies then serve as templates to make more copies. 4. In this way, just a few dozen cycles of replication can produce billions of copies of the DNA between the primers.

6. Lesson Summary Changing DNA Recombinant DNA molecules contain DNA from two different sources. Recombinant-DNA technology can change the genetic composition of living organisms. Plasmids are circular DNA molecules found in bacteria and yeasts; they are widely used by scientists studying recombinant DNA, because DNA joined to a plasmid can be replicated. A genetic marker is a gene that is used to differentiate a cell that carries a recombinant plasmid from those that do not.

7. Lesson Overview Lesson Overview Recombinant DNA Plasmids and Genetic Markers In addition to their own large chromosomes, some bacteria contain small circular DNA molecules known as plasmids. Joining DNA to a plasmid, and then using the recombinant plasmid to transform bacteria, results in the replication of the newly added DNA along with the rest of the cell’s genome.

8. Lesson Overview Lesson Overview Recombinant DNA Plasmid DNA Transformation Using Human Growth Hormone

9. Lesson Overview Lesson Overview Recombinant DNA Plasmids and Genetic Markers The new combination of genes is then returned to a bacterial cell, which replicates the recombinant DNA over and over again and produces human growth hormone.

10. Lesson Overview Lesson Overview Recombinant DNA Plasmids and Genetic Markers The recombinant plasmid has a genetic marker, such as a gene for antibiotic resistance. A genetic marker is a gene that makes it possible to distinguish bacteria that carry the plasmid from those that don’t. This plasmid contains the antibiotic resistance genes tet r and amp r. After transformation, the bacteria culture is treated with an antibiotic. Only those cells that have been transformed survive, because only they carry the resistance gene.

11. Lesson Overview Lesson Overview Recombinant DNA Recombinant DNA & Gene Splicing (6:15)

12. Lesson Summary Transgenic Organisms Transgenic organisms contain genes from other species. They result from the insertion of recombinant DNA into the genome of the host organism. A clone is a member of a population of genetically identical cells.

13. Lesson Overview Lesson Overview Recombinant DNA Transgenic Organisms The universal nature of the genetic code makes it possible to construct organisms that are transgenic, containing genes from other species. Like bacterial plasmids, the DNA molecules used for transformation of plant and animal cells contain genetic markers that help scientists identify which cells have been transformed.

14. Lesson Overview Lesson Overview Recombinant DNA Transgenic Organisms Transgenic technology was perfected using mice in the 1980s. Genetic engineers can now produce transgenic plants, animals, and microorganisms. By examining the traits of a genetically modified organism, it is possible to learn about the function of the transferred gene.

15. Lesson Overview Lesson Overview Recombinant DNA Transgenic Plants: Transforming a Plant with Agrobacterium

16. Lesson Overview Lesson Overview Recombinant DNA Transgenic Plants There are other ways to produce transgenic plants as well. When their cell walls are removed, plant cells in culture will sometimes take up DNA on their own. DNA can also be injected directly into some cells. If transformation is successful, the recombinant DNA is integrated into one of the plant cell’s chromosomes.

17. Lesson Overview Lesson Overview Recombinant DNA Transgenic Animals Scientists can transform animal cells using some of the same techniques used for plant cells. The egg cells of many animals are large enough that DNA can be injected directly into the nucleus. Once the DNA is in the nucleus, enzymes that are normally responsible for DNA repair and recombination may help insert the foreign DNA into the chromosomes of the injected cell.

18. Why do this? Transgenic animals can help create new medicines & produce valuable products. One of the first uses of transgenesis was to make the E. Coli bacteria produce human insulin, which could then be gathered cheaply, rather than having to be harvested from more expensive animals like pigs. A more contemporary example can be seen in the use of transgenic goats to product an anticoagulant in their milk. Mice can be modified so that researchers can observe specific responses their tissue has to diseases. This can lead to the development of drugs and treatments for humans suffering from those diseases People with sickle cell anemia can benefit from transgenic animals that contribute to gene therapy. A transgenic pig has been produced with the ability to synthesize human hemoglobin for use as a blood substitute. A transgenic cow has been bred with the ability to produce human lactoferrin, an iron-building milk protein and a potential antibacterial agent. A transgenic sheep can synthesize a protein that helps emphysema patients breathe more easily A transgenic goat has been developed to produce a protein needed by cystic fibrosis patients. GloFish®. These are zebrafish that have been modified to include genes that make them glow fluorescent colors. The fish were created in 1999 with the goal of helping to detect pollutants, but it quickly became apparent that they had huge potential as a novelty item. They come in three colors, with green GloFish® derived from the GFP protein from jellyfish, a red GloFish® derived from a type of sea coral, and a yellow GloFish® derived from a variant of the jellyfish protein. http://www.cliffsnotes.com/sciences/biology/biology/recombinant-dna-and- biotechnology/transgenic-animals http://www.transgenicanimals.info/pros-and-cons-of-transgenic-animals/http://www.wisegeek.com/what-are-transgenic-animals.htm

19. Lesson Overview Lesson Overview Recombinant DNA Transgenic Animals Recently it has become possible to eliminate particular genes by constructing DNA molecules with two ends that will sometimes recombine with specific sequences in the host chromosome. Once they recombine, the host gene normally found between those two sequences may be lost or specifically replaced with a new gene. This kind of gene replacement has made it possible to pinpoint the specific functions of genes in many organisms, including mice.

20. Lesson Overview Lesson Overview Recombinant DNA Cloning A clone is a member of a population of genetically identical cells produced from a single cell The technique of cloning uses a single cell from an adult organism to grow an entirely new individual that is genetically identical to the organism from which the cell was taken. Clones of animals were first produced in 1952 using amphibian tadpoles. In 1997, Scottish scientist Ian Wilmut announced that he had produced a sheep, called Dolly, by cloning.

21. Lesson Overview Lesson Overview Recombinant DNA Cloning Animals—Nuclear Transplantation