Lecture-7

Lecture-7 - #7 Recombinant DNA technology (IV) 1. Stem cell...

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Unformatted text preview: #7 Recombinant DNA technology (IV) 1. Stem cell 2. Plant transformation and cloning 3. Transgenic animals 4. Animal cloning 5. Therapeutic cloning Genetic engineering Genetic engineering (or protein engineering) is the process to design, modify, and produce recombinant genes or gene products for research or biotechnology applications. An engineered gene needs to be transformed into cells or organisms to see/get the effects. A gene may be engineered to:-express in different organisms-express in different conditions or at different levels-change the biochemical or physiological properties or to create novel properties of a protein . Why engineer genes? e.g.1. GM (genetic modified) crop-engineer better/new crops. GM crops have been used in agriculture since 1990's. e.g.2. Gene therapy to cure diseases - replace a "bad" gene with a "good" one. Not in practice yet, due to generally insufficient understanding of disease genes, lack of appropriate delivery system. Transgenic organisms are organisms stably transformed to contain the recombinant foreign DNA. This technology is the foundation for most molecular biology researches today. Unlike single cell organisms, multicellular organisms are difficult to transform. Transgenic organisms refer to multicellular organisms such as transgenic plants or transgenic animals. Two Keys in preparing transgenic organisms: (1) recombinant DNA must be delivered and integrated into the genome of the stem cell or equivalent of a host; (2) The transformed cell must be totipotent to have the ability to develop into a new individual. Transgenic organisms Stem cells are cells that can reproduce itself and differentiate/grow into other types of cells. There are many types of stem cells. Fertoilized eggs are totipotent (can give rise to a new organism). Embryonic stem (ES) cells are pluripotent (to give rise into all types of cells including itself). Mammals ES cells are isolated from the inner cell mass of blastocyst (early embryos). Under appropriate conditions, ES cells can also be totipotent. Somatic (or tissue specific) stem cells are progenitor cells of different tissues or organs, they are multipotent (to produce limited types of cells in addition to regenerate itself). Although different stem cells and somatic cells have the identical genomes, they may have different DNA modification, histone modification, and different gene expression. Most plant somatic cells can be induced to become totipotent or pluritoptent in vitro, but it is more difficult to do so for animal cells. 1. Stem cells Fertilized egg: totipotent-can develop into a new organism Embryonic stem cells : pluripotent-can develop into all types of cells Somatic stem cells : multipotent-can develop into many types of cells Fertilized egg (totipotent ) Male and female pronuclei Animal stem cells Plant stem cells Plant stem cells are located in the apical meristem , or the tip of a plant body, which gives rise to all types of cells in a mature plant....
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This note was uploaded on 02/20/2009 for the course LS 3 taught by Professor Lin during the Spring '06 term at UCLA.

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Lecture-7 - #7 Recombinant DNA technology (IV) 1. Stem cell...

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