Applied Genetics Selective Breeding and Genetic Engineering Selective
Applied Genetics Selective Breeding and Genetic Engineering
Selective Breeding • = crossing of plants or animals that have desirable traits to produce offspring with those traits • Increased strength • Leaner meat (less fat) • Disease resistance • Larger grain/fruit • Better taste
hybridization • = crossing two organisms (same genus/species, “kind”) with variations of particular trait(s) to produce offspring with a mixture of the trait(s)
• Offspring inherits traits of both parents • Donkey X horse = mule • Modern grains – corn, wheat • Ancient wild wheat X wild goat grass = nutritious hybrid wheat used for bread
• The greater the difference between “kinds” (genus/species) being hybridized, the more likely the hybrid will be sterile
Inbreeding • = crossing 2 organisms that have the same or similar trait(s) to produce animals with the same trait(s)
• Idea is to preserve the desirable traits • Organisms are genetically similar and can lead to negative consequences:
• Increased chances of inheriting disorders • Increased chances of contracting certain diseases • Decreased ability to adapt to environmental changes
Weird hybrids liger = cross between lion (father) and tiger (mother)
Weird hybrids • Tigon = cross between male tiger and female lion
• Beefalo/cattalo = bison x cow
• Hinny • Female donkey x male horse
Cama = male camel x female llama
Genetic Engineering • Process in which genes (sections of DNA) are taken from one organism and transferred to another
Recombinant DNA • Section of DNA is separated from strand of one organism • This is spliced into the DNA of another organism
• DNA is now combined • Modified DNA will cause cells to carryout processes in a different way
Products resulting from genetic engineering • Medicine Insulin, human growth hormone (produced by altered bacteria) Hepatitis B vaccine (produced by altered yeast cells)
• Genetically Modified Organisms (GMO) • Genetically Engineered Organisms (GEO) Transgenic crops GM foods Transgenic animals • Much of these are used in agriculture
transgenic goats (spider genes for web silk protein) (Nexia Biotechnologies) Used to manufacture Bio. Steel® & Protexia™
Agricultural uses • Herbicide-tolerant crops • Insecticidal crops • Better taste, texture, longer shelflife, larger size, better suited for mechanical harvesting
Potential problems • Cross-pollination of GM crops to wild varieties can cause weeds to become herbicide resistant • Insects may become quickly resistant to insecticides because of exposure to GM crops
• Predators that eat insects who have eaten GM crops can be affected in unknown ways • People who eat GM crops can be affected in unknown ways Toxic effects Pathogenic effects Allergic reactions Resistance to antibiotics
Terminator genes • Plants have been developed that have a trait that kills developing embryos in seeds so that seeds from crops cannot be saved & planted the following season
Warnings • Genes are now known to control more than one trait • By altering/changing a single gene, multiple traits may be changed in ways we can’t predict • Human genes are only a small percentage of the information contained in DNA (5% or less)…we don’t know what most of the rest does
• Humans have only 300 more genes than what are also found in mice… • “This tells me genes can’t possibly explain all of what makes us what we are. ” Craig Venter, president of Celera Genomics (Maryland firm that led one of the mapping teams for the Human Genome Project)
The Future…. • Chimera – organism or component composed of different genetic material
• So far… • Pigs with human blood • Mice with human brain cells • Sheep with human tissues in hearts & livers • Fusion of human & rabbit biomatter produced chimeric embryos
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