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GeneTechnology • I. Techniques used to manipulate DNA • http://www.youtube.com/watch?v=yc-s-WojU5Y&feature=related • http://www.youtube.com/watch?v=8rXizmLjegI\ • http://www.youtube.com/watch?v=TpmNfv1jKuA • A. Restriction Enzymes • These are special proteins that cut DNA at specific sites. • This can be used to isolate genes from other DNA on a chromosome for genetic testing, identification or gene therapy. Two different restriction enzymes Cut site= pathway the enzyme follows when it creates DNA fragments
B. PCR (polymerase chain reaction) This technique can make millions of copies of a particular DNA sequence Heating the DNA breaks the weak hydrogen bonds so the two sides separate. Special primers (complementary DNA) is added so only the gene of interest is copied. New DNA nucleotides are added to copy the gene of interest. This cycle of heating and cooling continues until there are millions of copies
C. Gel Electrophoresis This technique is used to separate cut up segments of DNA based on size. The pattern that is created is called a DNA fingerprint • 1. DNA is cut with restriction enzymes- this creates a mixture of different size pieces of DNA • 2. Cut up DNA is added to wells cut into a gel. The gel acts as a filter: small pieces move easily, large pieces move more slowly • 3. An electric current pushes DNA through the gel • 4. A dye is added to make the DNA visible as bands in the gel • ex. Lane one has 4 pieces of DNA or bands while lane 2 has only one band
5. In genetic testing several locations are tested to create the final DNA fingerprint. Two different alleles at A made two DNA fragments different in size from that found in individual #1 Two different alleles at location A so this created two different sized fragments (A5,A2) Two copies of the same allele at location B so only one band B2) Two different alleles at location B, one of which was the same size as the B allele in individual #1
II. Genetic Engineering • A. Recombinant DNA • Recombinant DNA is DNA combined from different sources. The genetic code is universal- cells in different species read genes and use this information to make a proteins in the same way. • http://www.youtube.com/watch?v=8rXizmLjegI&feature=related • 1. Steps used to create recombinant DNA Sticky ends connect because of bonds between complementary bases
2. Vectors and Recombinant DNA • A vector is a method used to add DNA to a cell. This can include such techniques as: • Heat shock • Direct injection • Using a virus Modified virus carries new gene. Virus infects the host cell New gene is used by the host cell to make a new protein
B. Products made through Genetic Engineering • Mutations cause the protein encoded by that gene to malfunction. There are two ways to treat such diseases: treat the symptoms with drugs or put in a normal, functioning copy of the gene into the patient. This last method is called gene therapy. • 1. Genetically Modified Bacteria- Humulin • Human insulin is the only animal protein to have been made in bacteria in such a way that its structure is absolutely identical to that of the natural molecule. This reduces the possibility of complications resulting from antibody production.
2. Gene Therapy • http://www.youtube.com/watch?v=gl2miunHTRI&feature=related Ex. Treating Hemophilia Using Gene Therapy Gene for missing protein is isolated using restriction enzymes The cells begin making the missing protein so blood will clot normally A virus adds the gene to human cells
Genetically Engineered Plants • a. Traditional Plant Breeding • http://www.youtube.com/watch?v=fkkHvsYXens • Genes can only come from the same species • Inbred (pure-breeding) parents are crossed to create a hybrid. The hybrid contains the traits from both parents. • This technique takes time to find the parents that have traits desired, and then cross to produce enough offspring. Double-Cross Hybrid produced by cross-breeding two different hybrids
b. Plants made using recombinant technology • http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter17/genes_into_plants_using_the_ti-plasmid.html • Genes can come from different species • This is a way of introducing traits that do not currently exist in a species. Isolate a new gene using restriction enzymes Use a bacteria that infects plants to add the new gene to the plant The plant begins making the protein coded for by the new gene
Example: Bt Corn http://www.youtube.com/watch?v=DbO_J0u8i-8 A gene from a bacteria called Bacillus thurgensis (Bt) is added to corn plants The plants make the Bt protein that kills insects when it is eaten