20_Lecture_Post - Biothechnology Overview The DNA Toolbox...

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Biothechnology Overview: The DNA Toolbox Sequencing of the genomes of more than 7,000 species was under way in 2010 DNA sequencing has depended on advances in technology, starting with making recombinant DNA In recombinant DNA , nucleotide sequences from two different sources, often two species, are combined in vitro into the same DNA molecule
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Methods for making recombinant DNA are central to genetic engineering , the direct manipulation of genes for practical purposes DNA technology has revolutionized biotechnology , the manipulation of organisms or their genetic components to make useful products An example of DNA technology is the microarray, a measurement of gene expression of thousands of different genes
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How can this array of spots be used to compare normal and cancerous tissues?
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DNA Cloning and Its Applications: A Preview To work directly with specific genes, scientists prepare well-defined segments of DNA in identical copies, a process called DNA cloning Most methods for cloning pieces of DNA in the laboratory share general features, such as the use of bacteria and their plasmids Plasmids are small circular DNA molecules that replicate separately from the bacterial chromosome Cloned genes are useful for making copies of a particular gene and producing a protein product
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Gene cloning involves using bacteria to make multiple copies of a gene Foreign DNA is inserted into a plasmid, and the recombinant plasmid is inserted into a bacterial cell Reproduction in the bacterial cell results in cloning of the plasmid including the foreign DNA This results in the production of multiple copies of a single gene
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Figure 20.2 Bacterium Bacterial chromosome Plasmid 2 1 3 4 Gene inserted into plasmid Cell containing gene of interest Recombinant DNA (plasmid) Gene of interest Plasmid put into bacterial cell DNA of chromosome (“foreign” DNA) Recombinant bacterium Host cell grown in culture to form a clone of cells containing the “cloned” gene of interest Gene of interest Protein expressed from gene of interest Protein harvested Copies of gene Basic research and various applications Basic research on protein Basic research on gene Gene for pest resistance inserted into plants Gene used to alter bacteria for cleaning up toxic waste Protein dissolves blood clots in heart attack therapy Human growth hormone treats stunted growth
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Using Restriction Enzymes to Make Recombinant DNA Bacterial restriction enzymes cut DNA molecules at specific DNA sequences called restriction sites A restriction enzyme usually makes many cuts, yielding restriction fragments The most useful restriction enzymes cut DNA in a staggered way, producing fragments with “ sticky ends .” Restriction site for the enzyme EcoRI
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