Ch. 13 Genetic Engineering Students know how genetic engineering is used to produce novel biomedical and agricultural products.

Content Objectives Explain what the purpose of selective breeding is. Explain why breeders might try to induce mutations. Describe how scientists make changes to DNA. Describe what occurs during cell transformation.

13-1 Selective Breeding Allowing only those individuals with desired traits to reproduce. Domesticated animals have been produced using this method Allows an increased opportunity for desired traits to be passed on. Different breeds of plant and animal are a result

Hybridization Crossing dissimilar individuals to bring together the best of each. Tend to be harder against disease (more resistant).

Inbreeding Continued breeding of individuals with similar characteristics. Maintains desired characteristics. Risks: due to close similarity, may bring together neg. effects.

Increasing Variation Done by mutations (which may be natural or induced). These will be inherited.

Polyploid Many sets of chromosomes. Fatal in animals New species of plants are produced when the chromosome number is doubled or tripled.

13-2 Manipulating DNA Genetic Engineering: Making Changes In the DNA code. DNA Extraction: Cells are opened (use a detergent to break cell and nuclear membranes and an alcohol to separate the DNA) Cutting DNA: Restriction Enzymes cut the DNA at a specific sequence of nucleotides. (The restriction enzyme (your scissors) cut the DNA after TGCA to solve the murder of Noah Sarque.) Separating DNA: Gel electrophoresis uses an electric current through a gel to separate the fragments of DNA. DNA is slightly negatively charged and is attracted to the opposite (positive) end of the gel. Smaller fragments move further though the gel than larger ones.

Using the DNA sequence Reading the sequence: (usually done with computers) Florescent dye is used to label each of the 4 bases. Restriction enzymes are used to cut the DNA after each base. Gel Electrophoresis separates the DNA by fragment size, but the color of the band indicates the nucleotide at the end of the fragment so the sequence can be read. Cutting and Pasting: Combining DNA from different organisms produces Recombinant DNA. Genes from a bacteria such as Bt toxin is inserted into corn as a pesticide. Making Copies: PCR or (Polymerase Chain Reaction) is a process used to copy sequences of DNA.

13-3 Cell Transformation During cell transformation, external DNA becomes a part of the cell. Recombinant DNA is DNA that is produced by combining DNA from two different sources. (Fish genes can be combined with tomato genes to make tomatoes tolerant to cold). Plasmids are circular DNA molecules found naturally in bacteria. A Genetic Marker is a gene that makes it possible to distinguish bacteria that carries the plasmid from those that do not. For example, antibiotic resistant genes are used as markers. All the bacteria are then treated with antibiotics. The only surviving bacteria are those with the antibiotic resistant gene marker. Foreign DNA can be inserted into plant and animal cells using bacteria. Ex: Genes that produce pesticide can be inserted into plant cells. The plants are then toxic to certain insects and do not need to be sprayed with chemical pesticides.

13-4 Applications of Genetic Engineering Transgenic organisms contain genes from other organisms.   Transgenic microorganisms are used to make insulin and growth hormone. Transgenic animals have been created with human growth hormone genes to make them grow faster and less fatty. Transgenic plants are a major part of our food industry and have genes to make them produce pesticide, resist frost, stay fresher longer and so on… A clone is a member of a member of the population of genetically identical cells produced from a single cell.

Examples of Applications Animals: mice – w/ human genes making their immune system act as ours so effects of medicine can be studied Livestock – w/ x-tra growth hormone so they grow faster and have more meat, less fat Plants: (GM) – genetically modified

Genetically Modified Crops Genetically modified organisms (GMOs) can be defined as organisms in which the genetic material (DNA) has been altered in a way that does not occur naturally. The technology is often called “modern biotechnology” or “gene technology”, sometimes also “recombinant DNA technology” or “genetic engineering”. It allows selected individual genes to be transferred from one organism into another, also between non-related species. Such methods are used to create GM plants – which are then used to grow GM food crops.

Why are GM foods produced? GM foods are developed – and marketed – because there is some perceived advantage either to the producer or consumer of these foods. This is meant to translate into a product with a lower price, greater benefit (in terms of durability or nutritional value) or both. To improve crop protection. The GM crops currently on the market are mainly aimed at an increased level of crop protection through the introduction of resistance against plant diseases caused by insects or viruses or through increased tolerance towards herbicides. Insect resistance is achieved by incorporating into the food plant the gene for toxin production from the bacterium Bacillus thuringiensis (BT). Virus resistance is achieved through the introduction of a gene from certain viruses which cause disease in plants. Virus resistance makes plants less susceptible to diseases caused by such viruses, resulting in higher crop yields. Herbicide tolerance is achieved through the introduction of a gene from a bacterium conveying resistance to some herbicides.