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DNA Technology: Tools for DNA Identification and Genetic Engineering

Explore how DNA technology is used for positive identification, improving crops, studying human predisposition for disease, and researching treatments for genetic diseases.

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DNA Technology: Tools for DNA Identification and Genetic Engineering

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  1. Chapter 13 GENE TECHNOLOGY

  2. Section 1: DNA TECHNOLOGY-Tools of DNA • Positive ID at a crime scene • Improvement of food crops • Human predisposition for disease • Research treatments for genetic diseases

  3. DNA Identification • No two human beings are identical genetically – except identical twins • Human beings have pretty much the same DNA except for 0.1% • Because of this difference, we can compare samples of humans for paternity, providing evidence, tracing human origins, identifying remains

  4. Noncoding DNA • We only use about 2% of our DNA • The remaining 98% is called noncoding DNA • This DNA contains many long, repeating varying nucleotide sequences called variable number tandem repeats – VNTR CACACA CACACA CACACA CACACA CACACA

  5. Noncoding DNA, cont. • The pattern of repeating nucleotides varies tremendously in the human population and can be used to make up a DNA profile

  6. Steps in DNA Identification • DNA Extraction (isolation) • PCR – polymerase chain reaction – the molecular photocopying process http://learn.genetics.utah.edu/content/labs/pcr/

  7. Steps, cont. – RE’s • Restriction enzymes – the molecular scissors • Enzymes that can cut (hydrolyze) DNA at specific sites. • Current DNA technology is totally dependent on restriction enzymes. • Restriction enzymes are endonucleases – they cut within the DNA

  8. Steps, cont. • Bacterial enzymes – used to cut bacteriophage DNA (viruses that invade bacteria) – why? • Different bacterial strains produce different restriction enzymes • The names of restriction enzymes are derived from the name of the bacterial strain they are isolated from

  9. Steps, cont. • Titles of restriction enzymes are derived from the first letter of the genus + the first two letters of the species of organism from which they were isolated. • EcoRI -  from Escherichia coli • BamHI - from Bacillus amyloliquefaciens • HindIII - from Haemophilus influenzae

  10. Steps, cont.

  11. Steps, cont. • Using this piece of DNA, cut it with Eco RI G/AATTC GACCG/AATTCAGTTAATTCG/AATTC • GACCG/AATTCAGTTAATTCG/AATTC

  12. Steps, cont. • Sticky ends – Creates an overhang. BamH1 • Blunts- Enzymes that cut at precisely opposite sites without overhangs. SmaI is an example of an enzyme that generates blunt ends

  13. Steps, cont. GE • Gel Electrophoresis – the molecular sieve • Separates nucleic acids or proteins based on size and charge DNA fingerprinting – • Banding pattern of the fragments of cut DNA on a special gel medium (agarose)

  14. Steps, cont. GEhttp://learn.genetics.utah.edu/content/labs/gel/

  15. Steps, cont. GE

  16. DNA Fingerprinting • A powerful tool to analyze VNTR • Odds are 1/100,000,000,000 that any two people will have the same genetic fingerprint!!!

  17. Recombinant DNA • The process of altering genetic material to make new substances – genetic engineering • The product is called recombinant DNA

  18. Cloning Vectors • Many copies of a desired gene can be cloned and its product harvested • This is accomplished by using a cloning vector – an organism that contains the desired gene and can multiply rapidly – this organism is usually a bacterium • Vector = carrier • http://www.bioteach.ubc.ca/TeachingResources/Applications/GMOpkgJKloseGLampard2.swf

  19. Probes • A strand of DNA or RNA that is radiolabeled • It is used to “fish” for the desired gene when either carrying out recombination, or identifying unknown DNA

  20. Section 2: The Human Genome • Huge research project, conducted over 13 years, sequenced and identified 20-25,000 human genes • Findings include: 2% coding DNA, RNA useful in regulating gene expression, transposons shuffle to make new genetic combinations

  21. Section 3: Genetic Engineering • Gene therapy – treat a genetic disorder by inserting a functional gene • CFTR gene in cystic fibrosis, a temporary fix • Gene inserted into a nonpathogenic virus and introduced into nasal spray • Not completely successful; lung tissue is deep, cells slough off, rejection responses

  22. Cloning

  23. HELLO DOLLY!!! • Dolly died prematurely as she had short telomeres = ends of chromosomes – like aglets! • Currently animals can be cloned to grow up organs for human transplants

  24. Other applications • GMOs – genetically modified organisms, crops • Increase yield, make crops weather and pest resistant, increase nutritional value • Controversy related to genetically modified (GM) food : risk of harm from GM food, whether GM food should be labeled, the role of government regulators, the effect of GM crops on the environment, the impact of GM crops for farmers, the role of GM crops in feeding the growing world population

  25. GM foods, cont. • Soy, corn, dairy • Buy organic, 100% grass fed beef • Buy local • PLU codes – 5 numbers beginning with a 9 = organic; 4 numbers = conventional; 5 numbers beginning with an 8 = GM

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