GeneTechnolog y 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.
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
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
Suspect #2’s DNA matches that found at a crime scene
Sticky ends connect because of bonds between complementary bases
Modified virus carries new gene.
Virus infects the host cell
New gene is used by the host cell to make a new protein
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
Double-Cross Hybrid produced by cross-breeding two different hybrids
Isolate a new gene using
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
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