Heredity Test 4

Heredity Test 4 - Genetic Engineering Key Points: Gene...

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Genetic Engineering Key Points: Gene Engineering in Plants o DNA can be introduced via a gene gun or agrobacterium infection o Production of plants with novel properties Getting genes into plants, strategy 1: gene gun Strategy 2: Ti plasmid (tumor inducing) o Agrobacterium tumefaciens: bacterial plant pathogen Induces cells to multiply uncontrollably o Ti Plasmid: integrates into the plant’s genome and induces the growth defect o Scientists have modified the Ti plasmid to transfer other genes into plants o Step 1: foreign gene is transferred into Ti o Step 2: modified plasmid is incorporated into the plant genome Genetically modified crops o Insect/herbicide resistance o 60-70% of products have genetically modified corn, soy, other products Gene Therapy Key points o Gene can be delivered to cells without a functional copy of the gene o Activity of a gene can be reduced in relevant cells Treating genetic Disease o Disease management Replace missing proteins Numerous other strategies (diet) Gene delivery strategies o In vivo gene therapy In the real setting, directly into patient, uses virus to affect many cells o Ex vivo gene therapy Cells are removed, the gene is added to the cells, cells are returned o In situ gene therapy Delivers gene into a very specific location in the body, such as for cancer Problems: o DNA does not generally pass the cell membrane (large, non-polar, negatively charged) o DNA will not replicate without an origin of replication Vectors used in gene therapy: o Vehicle to deliver the gene to a site o Mostly viruses Adenovirus, retrovirus, naked/plasmid DNA, lipofection, pox virus, herpes simplex Retrovirus converts RNA genome to DNA (reverse transcriptase)
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o Bacteria can’t be used because it doesn’t enter genes into the cell, just replicates it Eliminating unwanted genes o Small RNAs directed against unwanted RNA’s (not genes) can eliminate the gene o Potentially useful for treating infectious diseases and other diseases o Important pathway: RNA interference (RNAi) Cuts RNA into small pieces Protein complexes attach, find target mRNA Either degrade the mRNA or block translation o Not a direct method, but can silence specific genes How well does it work? o First trial: Adeonsine Deaminase Deficiency DEoxyadenosine must be destroyed Leads to Deoxy ATP buildup Bubble-boy disease Therapy: Injections of PEG-ADA (protein); increased ADA levels and T cell survival Multiple injections required Bone marrow transplant Gene therapy: o Ex vivo therapy o Long term immune restoration occurred Other patients have had complications (Leukemia) o Risk of leukemia is decreased if gene therapy is done after 3 months of age o Ornithine Transcarbamylase (OTC) Deficiency of OTC: x-linked recessive mutation
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Heredity Test 4 - Genetic Engineering Key Points: Gene...

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