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icimmy
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What are reasons to make transgenic animals?
- To make a model animal to study animal diseases
- Introduce economical important traits in farm animals
- For production of antibody and growth hormones
- Help transfer genes across species
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What methods are used in gene transfer?
- DNA microinjection
- Embryonic stem cell-mediated gene transfer
- Retrovirus-mediated gene transfer
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What are the steps in DNA microinjection?
- Identify the gene of interest
- Clone the gene in the proper vector
- Microinject the cloned gene directly into the pronucleus of a single fertilized egg before first cell division occurs
- Implant the egg into surrogate mother
- Allow embryo to develop to birth
- Demonstrate that the foreign gene has been incorporated into the host genome and it is heritable in at least one offspring.
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What are the potential problems in microinjection?
- Few injected eggs survive
- The gene inserts itself into chromosome at random
- Not all of the cells in the animal receive the gene
- The gene is not expressed in large enough amounts
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What is embryonic stem cell gene transfer?
- Producing differentiated cells from undifferentiated cells, by maintaining the potential of undifferentiated stem cells
- Used for targeted gene replacement (put the gene on the right chromosome)
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What are the steps in embryonic stem cell gene transfer?
- ES cells removed from embryo
- Transfection- Gene of interest is inserted in the the embryo
- The gene is targeted by homologous recombination and selective markers
- The ES cells with the correct gene are inserted into blastocysts (partially developed embryos) which are implanted into the mother animal
- Offspring are screened for trait of interest
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What are the uses of embryonic stem cells?
- Study human diseases
- Drug discovery
- Study growth and developement
- To inactivate or insert gene
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What are the two ways of gene targeting?
- Knock-in - Insert genes into specific site on chromosome
- Knock-out - Remove a gene or part of a gene to inactivate it
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How is a retrovirus used to integrate genes into a recipient organism?
- By infecting the organism with virus carrying the gene
- The desired gene can be integrated into the host chromosome
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What make an animal transgenic?
- Animals have genes from other species
- Genes either knock-in or knock-out
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What are the uses of transgenic animals?
- They are modified to resist diseases and environmental stress
- They are used to manufacture proteins, clotting factors, hormones, growth factors
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What is Xenotransplantation?
The use of animal organs in human patients
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What is the animal of choice for Xenotransplantation and why?
- Pigs
- They are easy to raise and breed
- Have similar sized organs
- Can be genetically engineered and cloned
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What are the concerns about xenotransplants?
- Ethical concerns
- Loss of litter mates
- Fear of diseases
- Required method to screen PERV free organ and organ is not rejected
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What are some animal health concerns
- Foot and mouth disease
- Mad cow disease
- Coccidiosis
- Trypanosmoiasis
- Theileriosis
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What is artificial insemination?
- Allows genetically desirable animals to be bred more efficiently and frequently
- Increase genetic diversity of endangered animals
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What is conservation biology?
It is used to preserve and protect endangered species of animals
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What techniques are used in conservation biology?
- Invitro fertilization for controlled breeding
- Cryopreservation of gametes
- Embryo transfer-preserving fertilized eggs
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What are the causes for concern for animal clones?
Animals have many problems- Early death, low cloning success, oversized animals, physical deformities, medical problems
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