Recombinant DNA Technology

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Recombinant DNA Technology

• Genetic Engineering and Applications of DNA
  Technology

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Genetic Engineering

• Genetic engineering is when DNA is cut or cleaved
  from one organism into small fragments and then
  inserted into a host organism of the same or a
  different species
• Recombinant DNA is made by connecting or
  recombining fragments of DNA from different
  sources

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Transgenic Organisms

• Recombinant DNA can be inserted into a host
  organisms chromosomes and the organism will use
  the foreign DNA as if it were its own
• When an organism contains foreign DNA it is
  called a transgenic organism
• There are three steps to the process
• 1. the foreign DNA fragment is isolated
• the DNA fragment is attached to a carrier
• 3. the DNA is transferred into the host organism

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Restriction Enzymes Cleave DNA

• To isolate the DNA fragment it must be cut from
  the chromosomes
• Restriction enzymes are bacterial proteins that
  have the ability to cut both strands of the DNA
  molecule at a specific nucleotide sequence
• There are hundreds of restriction enzymes

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Vectors Transfer DNA

• Fragments of DNA can not just be put into another
  organism
• A vector is the means by which DNA from another
  species can be carried into the host cell
• Vectors can be biological or mechanical

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Vectors

• Biological vectors include viruses and plasmids
• A plasmid is a small ring of DNA found in a
  bacterial cell
• Two examples of mechanical vectors are a
  micropipette that is inserted into a cell and a
  microscopic metal bullet coated with DNA that is
  show into the cell with a gene gun

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Gene Cloning

• After the foreign DNA has been inserted into a
  plasmid the recombined DNA is transferred to a
  bacterial cell
• The plasmid can make copies of itself and can
  make up to 500 copies per bacterial cell
• An advantage of using bacterial cells is that
  they reproduce quickly

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Gene Cloning

• Clones are genetically identical copies
• Each identical recombinant DNA molecule is called
  a gene clone
• Plasmids can also be used to deliver the genes to
  animal or plant cells, when then use the
  recombinant DNA
• The host cell will make copies of the recombinant
  DNA each time it divides

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Cloning of Animals

• The most famous cloned animal is Dolly
• She was a sheep cloned in 1997
• Other mammals such as mice, cattle, goats and
  pigs have been cloned
• This could help ranchers clone productive,
  healthy animals

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Polymerase Chain Reaction

• One way to make copies of DNA outside of an
  organism is polymerase chain reaction
• This involves heating the DNA until the DNA
  strands separate from each other
• The machine can then make copies
• The PCR can make over 1 million copies in a day

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Sequencing DNA

• Genetic engineering can also let scientists
  determine the correct order of DNA sequences so a
  mutation can be identified
• Millions of copies of the DNA is made using PCR
• The strands are separated from one another
• The single-stranded fragments are put into four
  different test tubes
• One for each base (A, C, T, G)

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Sequencing DNA

• One nucleotide in each tube is tagged with a
  different fluorescent color
• The reactions produce complementary strands of
  different lengths
• These strands are separated by gel
  electrophoresis which produces a pattern
• The short strands travel the farthest while the
  long strands travel the shortest distance

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Applications of DNA Technology

• Industry
• Species of bacteria have been engineered to
  produce chemical compounds used by humans
• Scientists have modified E.coli to produce the
  indigo dye in denim blue jeans
• Bacteria is also used in the production of
  cheese, laundry detergent, pulp and paper
  products and sewage treatment

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Recombinant DNA in medicine

• Pharmaceutical companies are using recombinant
  DNA to treat human diseases
• Recombinant bacteria is used for the production
  of the human growth hormone to treat pituitary
  dwarfism
• Also used to produce insulin
• Human antibodies, hormones, vaccines, enzymes and
  other compounds needed to treat and detect
  disease are being used

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Transgenic Animals

• Scientists can study disease by using transgenic
  animals
• Mice are often used
• Mice and human chromosomes are similar
• The roundworm and fruit fly (Drosophilia
  melangaster) are also used

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Recombinant DNA in agriculture

• Crops have been produced that taste better, stay
  fresh longer, and are disease resistant
• Products such as corn, broccoli, cotton and
  potatoes have been developed to be resistant to
  certain insects
• There is also research to put more vitamins in
  crops to be used in developing countries