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Chapter 20 Notes: DNA Technology

Chapter 20 Notes: DNA Technology. Understanding & Manipulating Genomes. 1995: sequencing of the first complete genome (bacteria) 2003: sequencing of the Human Genome mostly completed These accomplishments depended on new technology:

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Chapter 20 Notes: DNA Technology

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  1. Chapter 20 Notes: DNA Technology

  2. Understanding & Manipulating Genomes • 1995: sequencing of the first complete genome (bacteria) • 2003: sequencing of the Human Genome mostly completed • These accomplishments depended on new technology: • Recombinant DNA: DNA from 2 sources (often 2 species) are combined in vitro into the same DNA molecule • Called Genetic engineering: direct manipulation of genes for practical purposes

  3.  DNA technology has launched a revolution in the area of: BIOTECHNOLOGY: the use of living organisms or their components to do practical tasks -microorganisms to make wine/cheese -selective breeding of livestock -production of antibiotics -agriculture -criminal law

  4. **Practical goal of biotech = improvement of human health and food production

  5. Ch 20 looks at: • Main techniques for manipulating DNA • How genomes are analyzed & compared at the DNA level • Practical applications of DNA technology (including social & ethical issues)

  6. “Toolkit” for DNA technology involves: -DNA vectors -host organisms - restriction enzymes

  7. VECTORS = carriers for moving DNA from test tubes back into cells -bacterial plasmids (small, circular DNA molecules that replicate within bacterial cells) -viruses

  8. HOST ORGANISMS: bacteria are commonly used as hosts in genetic engineering because: 1)DNA can easily be isolated from & reintroduced into bacterial cells; 2) bacterial cultures grow quickly, rapidly replicating any foreign genes they carry.

  9. RESTRICTION ENZYMES = enzymes that recognize and cut short, specific nucleotide sequences (called restriction sites) -in nature, these enzymes protect the bacterial cell from other organisms by cutting up their foreign DNA

  10. Restriction Enzymes (cont.)… most restriction sequences are symmetrical in that the same sequence of 4-8 nucleotides is found on both strands, but run in opposite directions restriction enzymes usually cut phosphodiester bonds of both strands in a staggered manner producing single stranded “sticky ends” 

  11. Restriction Enzymes (cont.)… “sticky ends” of restriction fragments are used in the lab to join DNA pieces from different sources (complementary base pairing) *RECOMBINANT DNA unions of different DNA sources can be made permanent by adding DNA ligase enzyme (form covalent bonds between bases)

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