Genetic Engineering and
The use of living organisms for practical
How long has biotechnology been around?
Since man began planting crops, breeding
livestock and brewing beer
years! It is even mentioned in the Bible.
Today we can alter an animal or plant one
gene at a time, more rapidly and precisely
producing altered organisms.
Even the boundaries between species are
becoming blurred as we move genes from
bacteria into plants and animals.
polyester blends grown in cotton plants
Alter biochemical pathways :
Damage genes for ethylene production
Damage genes for polygalacturonase
A DNA molecule consisting of two or more
DNA segments that are not found together
We can insert a gene into a plasmid, and
infect a cell with the plasmid.
DNAase and RNAase cut up genetic
material at random
sequences of bases, called
Bacteria produce many different restriction
enzymes that cut genetic material at different
Some make “blunt” ends: ATTC GGATC
Some make “sticky” ends: ATTCGG ATC
These pieces are
For recombinant DNA to be useful, we
needed to be able to
quantities of a gene.
One way is to use plasmids.
A plasmid can be cut down to an origin of
replication and one or more genes for
Now any other gene can be inserted into the
plasmid and the bacterium will copy it.
polymerase chain reaction
Now we can easily copy or
in the lab.
Produce two oligonucleotides that match
up with the DNA before and after the
DNA you want to copy.
Heat DNA to break the hydrogen bonds
and open the DNA.
3. Add oligonucleotides (primers)
4. Cool, allowing primers to bind to DNA
5. Add nucleotides and DNA polymerase.
Can now do the whole thing at higher
temperatures using the more stable
PCR can be applied to :
Amplifying DNA in a drop of blood
Find DNA from the HIV virus
Find early signs of cancer
Find genetic defects in human embryos
Examine the DNA of ancient organisms
If we want to put eukaryotic DNA into
prokaryotic DNA we have one more
Introns! Bacteria do not have a means for
dealing with introns, so we must give them
a copy of a gene without introns in it.
Start with mature mRNA.
Use reverse transcriptase to copy it into
This DNA is called complimentary or cDNA.
Unfortunately, some proteins need to be
modified after they are translated, which
can only be done in eukaryotic cells.
To get our gene into another cell we need a
a means to carry it there.
This vector can be a plasmid or virus or
another means of carrying the DNA into
Now we can have bacterial or eukaryotic
cells making useful proteins
vaccines, enzymes, drugs and human
We could also make new proteins:
“Abzymes” antibodies that act as enzymes
that would attach to and break up synthetic
chemicals polluting the environment.
Recombinant DNA can be inserted into the cells
of whole plants and animals
Insulin in the milk of cows, polyester blends
from cotton plants.
To produce an organism that has the transgene
in all the appropriate cells of the organism the
DNA must be added to:
the original single celled
this is called
germ line gene
So far, only one transgenic organism is born
for every hundred zygotes.
Few eggs incorporate the DNA
DNA is inserted into the chromosome at
can disrupt key genes and kill organism
Replacing one gene with another is easy in
prokaryotes but difficult to do in animals.
It is easier to create a genetic
in which a particular gene has been
removed or disabled.
This can be used to remove a harmful
gene, for producing research animals and
for studying the effects of a specific gene.
Genetically engineering plants is common
>2/3 of all genetically engineered plants on
earth are grown in the U.S.A.
Mostly corn, soybeans and cotton
It is relatively easy to insert genes into plants:
We can use the Ti plasmid in the bacterium
We can also use a gene gun
gold or tungsten are coated with
recombinant DNA and shot into young plant
tissue which is chopped up and grown in
Corn which has an natural insecticide
Soybeans that resist a root
“Roundup Ready” seeds resist the
oil” corn makes twice the normal
amount of oil
Tobacco plants that manufacture
antibodies and vaccines
What are the risks?
These new genes can infect wild strains
A gene for herbicide resistance could find
its way into weeds
Danger to animals that interact with the
Dispersing genes of viruses and bacteria
that cause disease in plants
Dispersing genes for antibiotic resistance
Tendency of these genes to jump to other
Problems with patents:
Farmers that save seeds for next year’s crop
Pollen that blows or is carried into neighboring
Ideally, we could use these techniques to
treat genetic diseases such as cystic
fibrosis and hemophilia
Engineer rice to contain vitamin A and
Vaccines in bananas
Tomatoes with cancer fighting substances
Production of fibrinogen for bandages
Right now we can test for genetic diseases
without being able to do anything about
What if your insurance company finds out?
Breast cancer genes
Peanut genes in other plants?
Jesse Gelsinger of Tuscon, AZ was one of
the first deaths recognized to be caused
by attempted gene therapy.
Risk death of clones and pregnant mother
Abnormalities in pregnancy
Half of all clones of large mammals have
abnormalities of the heart, lungs and other
Do clones age faster than normal?
Where do “undesirable” traits stop?
Can we patent human genes?