Download Transgenic Organisms

Selective breeding – controlled breeding for
desired characteristics; takes advantage of
naturally occurring genetic variation – Fig. 13 – 1
What are some organisms that are good
examples of selective breeding?
1. hybridization – breeding technique that
involves crossing dissimilar individuals to
bring together the best traits of both
organisms
2. inbreeding – mating between organisms that
are genetically similar: promotes
preservation of desired characteristics;
decreases genetic variation
X
Increasing genetic variation can be accomplished
by inducing mutations
1. Bacteria – radiation or chemicals can cause
“beneficial mutations” – Fig. 13-3
2. Plants – chemicals that prevent chromosomal
separation lead to polyploidy (What
advantages do these plants have?)
3. Induced mutations can also be used to study
the function of proteins
How do scientists change/manipulate DNA?
1. DNA extraction – remove DNA from the cell
2. DNA cutting – restriction enzymes “cut” DNA
at very specific nucleotide sequences
Fig. 13-5
Restriction Enzyme
http://www.youtube.co
m/watch?v=yc-sWojU5Y&feature=relat
ed
How do scientists change/manipulate DNA?
3. DNA separating – gel electrophoresis uses an
electrical current to separate fragments of
DNA based on size – Fig. 13-6
Gel Electrophoresis
http://www.sumanasinc.com/webcontent
/animations/content/gelelectrophoresis.h
tml
Reading the sequence allows the study of specific
genes – Fig. 13 -7 (Sanger Sequence)
1. Start with a single strand of DNA with
unknown sequence
2. Mix this strand with DNA polymerase and a lot
of nucleotides; some of the nucleotides are
“tagged” with dye
3. each time a “tagged” nucleotide is added
replication stops
4. Using gel electrophoresis complementary
DNA strand is “read”
Sanger Sequencing
Videos
http://www.youtube.co
m/watch?v=aPN8LP4Y
xPo&feature=related
http://www.youtube.co
m/watch?v=6ldtdWjD
wes&feature=related
A technique by which any segment of DNA can be
quickly amplified (copied many times) – Fig. 13-8
1. DNA is separated and added to a mixture of
nucleotides and enzymes
2. New complementary strands are made
3. Cycle is repeated many times
http://www.youtube.com/watch?v=JRAA4C2OPwg&featur
e=related PCR Animation
PCR Song
http://www.youtube.com/watch?v=x5yPkxCLads
Some bacteria can take up naked DNA from the
surroundings.
1. Plasmid – a small, circular, self-replicating DNA
molecule separate from the bacterial
chromosome
2. Assimilated foreign DNA is taken up by the
plasmid
3. Offspring of the recipient bacterium will carry a
new combination of genes
4. Genetic marker – a gene that produces a known
protein that can be used to “mark” bacteria that
have taken up foreign DNA
Plant Transformation – Fig. 13-10
1. Plasmids that normally infect plant cells can be
used as carriers of foreign DNA
2. Whatever gene is taken up is then expressed by
the plant cell
3. What are some advantages and disadvantages of
this technology?
The bacterium can be
used to introduce
foreign DNA into plant
cells. If the
transformation is
successful, the DNA
will be integrated into
one of the cell’s
chromosomes.
Animal Transformation – Fig. 13-11
1. Eggs cells are large enough to take up foreign
DNA
2. DNA is inserted manually and enzymes normally
present in the cell to repair DNA help to insert
the foreign DNA
3. Technique can be sued to study specific functions
of a gene
Transgenic organisms contain genes from another
species; possible because of the universal nature of
the genetic code – Fig. 13-12
1. Microorganisms – easy to grow, divide rapidly,
can be used to produce human proteins
2. Animals can be used to improve food supply, or
to study effect of human diseases
3. Plants – genes can be implanted that provide
plants with natural insecticides, or resistance to
various chemicals
This transgenic tobacco
plant, which glows in
the dark, was grown
from a tobacco cell
transformed with the
firefly luciferase gene.
The plant illustrates
how DNA from one
organism contains
information that can
specify traits in another
organism.
Cloning – A clone is a lineage of genetically identical
individuals or cells
1. Basic cloning technique – Fig. 13-13 KNOW!!!
In early 1997, Dolly
made headlines as the
first clone of an adult
mammal.
Why did Dolly not look
like her foster mother?
The adult sheep is
Dolly. The lamb is
Dolly’s first offspring.,
called Bonnie. The fact
that dolly was cloned
did ot affect her ability
to produce a live
offspring. Why might
it be important for
cloned animals to be
able to reproduce?