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Genetic Influences and Technology Genetic Technology outline 1. 2. 3. 4. 5. How environment affects genes Genetic modification Transgenic organisms Gene therapy Cloning 6. 7. Selective breeding Hybridization Inbreeding Test cross As an organism develops, many factors can influence how the gene is expressed, or even whether the gene is expressed at all. For example, flowers called hydrangea bloom blue if grown in acidic soil and bloom pink if grown in non acidic soil. Environmental Influences on genes temperature nutrition light chemicals bacteria/viruses Influence of external environment arctic foxes In the summer, enzymes produce brown pigment. These enzymes don’t work in the cold, therefore, no pigment is produced in the winter. The fur color of a Siamese cat is influenced by temp. The ears, nose, paw, and tail are darker than the rest of the body because those body parts are cooler than the normal body temp. The genetic code is universal, so genes can be transferred from one organism to another, even if they are members of different species. Genetically modified organism (GMO): organism that has had genes transferred to it from another organism *also called transgenic organisms Genetic modification: process of transferring genes from one organism to another ex. 1 transfer a gene for making growth hormone from cattle to chickens ex. 2 transfer a gene for making human insulin from human to bacteria Transgenic organisms – plants or animals that contain genes from an organism of a different genus. Example – inserting a gene from a firefly into a tobacco plant. The Result – a glowing tobacco plant. In this example the tobacco plant is the transgenic organism. Maize (corn) crops are often damaged by borer insects. A gene from a bacterium (Bacillus thuringiensis) has been transferred to maize. The gene codes for a bacterial protein called Bt toxin that kills corn borers feeding on the maize Other recent examples: 1. 2. 3. Bacteria that can absorb arsenic *useful to remove poison from groundwater in places like Bangladesh Algae that can make jet fuel Ruppy, the glow-in-the-dark puppy (2009) Gene Therapy Treatment of a genetic disease by altering the genotype. Involves the replacement of defective genes. Cloning Producing identical copies of genes, cells, or organisms. Clone: a group of genetically identical organisms or a group of cells artificially derived from a single parent cell. Gene Cloning Clones are genetically identical copies. In 1997, a sheep named Dolly was cloned, and since then various other mammals including mice, goats, cattle and pigs have been cloned. Applied Genetics Selective Breeding – Choosing the organisms with the most desirable traits and breeding them. This has been done for centuries with plants as well as animals. Ex. Horses, corn Through selective breeding, farmers can increase the frequency of a certain allele within a population. This is the essence of genetic technology. Types of Selective Breeding: Hybridization: crossing dissimilar individuals to bring together the best of both *produces hybrids that are hardier than parents *ex. Corn, mules Inbreeding – mating between closely related individuals. Risks: because genetically similar, recessive alleles causing genetic defects appear more often ex. Blindness, deafness, joint problems Horses and dogs are examples of animals where breeders have created pure breeds using inbreeding. In many plants, crossing pure breeds results in bigger and more productive hybrids. Test Cross Testcross: crossing individual of unknown genotype with one of known genotype (usually homozygous recessive) example: There is a black sheep but we don’t know if it is BB or Bb but if we mate it with a white sheep (since we know it is bb) then if any white offspring = dad is Bb but if all black offspring = dad is BB