Genetics_ an Overview by dfhdhdhdhjr

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   Chapter 13
Genetic Engineering
    zony
           Dolly
In this chapter:
  13.1 Changing the Living World

  13.2 Manipulating DNA

  13.3 Cell Transformation

  13.4 Applications of Genetic Engineering



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13-1 Changing the Living World
    What forces gave rise to the speed of a
    greyhound, the courage of a German
    Shepherd, and the herding instinct of a
    Border Collie?




                                              3
SELECTIVE BREEDING
      We have bred dogs for thousands of
       years by selective breeding.

      Selective Breeding= allowing only
       those organisms with desired
       characteristics to produce the
       next generation.

      Ex. Speed of a greyhound

                                           4
TYPES OF SELECTIVE BREEDING

   Hybridization= crossing dissimilar individuals to
     bring the best of both organisms together.
   http://www.molyworld.net/aa/crossesa.htm
   http://www.hemmy.net/2006/06/19/top-10-hybrid-
     animals/

   Ex. Disease resistant plant with a food-
     producing capacity plant

   Inbreeding= continued breeding of individuals
     with similar characteristics.

                                                       5
RISKS OF INBREEDING

                        Persian Cat
                        flat face= breathing
                        problems




  Shar-pei
  Huge rolls of skin=
                                               Basset hound
  Skin disease
                                               Droopy, baggy eyes=
                                               Prone to eye infection




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7
INCREASING VARIATION
 How does one increase genetic variation?

  By inducing mutations which is the
  ultimate source of genetic variability
  through radiation or chemicals.

 Two examples:
 New bacteria- oil-digesting bacteria used
  in cleaning up oil spills
 New plants- polyploidy. Having many sets
  of chromosomes leading to larger and
  stronger plants.                           8
REVIEW
     • Give an example of selective
       breeding.

         – Any domesticated animal


     • What is the ultimate cause of
       genetic variation?

         – Mutations


                                       9
13-2 Manipulating DNA
      How are changes made to DNA?

      Through Genetic Engineering:
      1. Extract DNA from cells
      2. Cut DNA into smaller pieces
      3. Place DNA into electrophoresis
         chamber
      4. Identify the sequence of bases
      5. Make unlimited copies

                                          10
 DNA Restriction Enzymes
• Evolved by bacteria
  to protect against
  viral DNA infection
• Endonucleases =
  cleave within DNA
  strands
• Over 3,000 known
  enzymes




                           11
Enzyme Site Recognition
• Each enzyme digests
  (cuts) DNA at a specific
  sequence = restriction
  site                       Restriction site


• recognize 4- or 6- base                       Palindrone
  pair,
• palindromic sequences
  (eg GAATTC)




                                Fragment 1              Fragment 2




                                                                     12
GEL ELECTROPHORESIS




                      13
PCR-Polymerase Chain Reaction
      –Makes copies of DNA

        •Used in Forensic
        Investigations
        •Research

        •Developed by Kary Mullis

        •Uses DNA (Taq)
        polymerase from Ancient     1993 Nobel for Chemistry
        Hot Springs Bacteria
        (Archea Bacteria)




                                                           14
What is a plasmid?
      • A circular piece replicating DNA




                                   ori

                                         A


   Originally evolved by bacteria
   May express antibiotic resistance gene or
    be modified to express proteins of interest

                                                  15
What is transformation?
    • Uptake of foreign DNA, often a
      circular plasmid

                          GFP




                            Antibiotic Resistance




                                               16
13-4 Genetic Engineering
 CLONE: member
 of genetically
 identical cells
 produced from a
 single cell.

 In 1997, Dolly was
 the first mammal
 to be successfully
 cloned.



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