Download A. Restriction Enzymes

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
1. These are special proteins that cut DNA at specific sites.
2. 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 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 A made
two DNA fragments different in
size from that found in
individual #1
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
II. Genetic Engineering
A. Recombinant DNA
Recombinant DNA is DNA combined from different sources. The genetic code is universalcells 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:
o Heat shock
o Direct injection
o 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
3. Genetically Engineered Plants
a. Traditional Plant Breeding
http://www.youtube.com/watch?v=fkkHvsYXens
o Genes can only come from the same species
o Inbred (pure-breeding) parents are crossed to create a hybrid. The hybrid contains the traits from both
parents.
o 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
o Genes can come from different species
o 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