Transcript GENETIC ENGINEERING

GENETIC ENGINEERING
Genetic engineering examples include taking the gene that programs poison in
the tail of a scorpion, and combining it with a cabbage. These genetically
modified cabbages kill caterpillers because they produce scorpion poison
(insecticide) in their sap. Potatoes have been engineered to resist pests by
producing a chemical coded for by a frog gene.
Genetic engineering also includes insertion of human genes into sheep so that
they secrete alpha-1 antitrypsin in their milk - a useful substance in treating
some cases of lung disease.
Genetic engineering works
because
there
is
one
“language of life” (universal
genetic code): human genes
work in bacteria, monkey genes
work in mice, pepper plant
genes work in bananas and
spider
genes
work
in
goats. There is no limit, in
theory,
to
what
genetic
engineering could produce!
Genetic engineering has
created a chicken with
four legs and no wings.
Scientists were studying
the genes that control
limb formation in embryo
development.
What is genetic engineering?
• the use of technology to change the
genetic make-up of cells to produce a
new and useful result
Is genetic engineering a new idea?
• Humans have been selecting and breeding
organisms with desired traits for thousands
of years. Some examples:
– “Seedless” oranges
– Pluots: Plum-apricot hybrid
Comparing selective breeding and
genetic engineering
In selective breeding (think
Mendel’s peas), we are combining
two traits to get a mixture of results
In genetic engineering, a single gene,
a half page recipe in the 52-thousandpage set of recipe books, can direct
the plant to make new traits or remove
them
Comparison
How does genetic engineering work?
• First, a desired gene in an
organism must be
identified and isolated.
• Once isolated, the gene is
further modified in the
lab
• The modified gene is
inserted into a vector
(like a bacterium or virus)
and the vector “delivers”
the gene to the desired
organism.
http://cmbi.bjmu.edu.cn/cmbidata/therapy/research/re02/021.htm
How it works:
Example: Insulin Production
• Protein that codes for insulin production is cut
from human DNA using restriction enzyme
(EcoRI)
Example: Insulin Production
• Plasmid (from E.coli) is
also cut with EcoRI
– Sticky ends are now
exposed on both human
DNA and plasmid DNA
Example: Insulin Production
• Ligase seals sticky
ends of desired DNA
and plasmid DNA
• Recombinant DNA is
inserted into a
bacterium
How Did They Do That?
Virus
Mouse cell
1.
Jellyfish make a protein that
causes them to glow in some
types of light.
Jellyfish cell
2.
The glowing gene is taken from
a jellyfish cell and inserted into
an empty virus cell
Virus inserting
their DNA into
a cell
3.
The genetically engineered virus
attaches itself to the fertilized
mouse egg cell.
4.
The virus delivers the glowing
gene into the egg cell nucleus,
where it joins the mouse DNA.
5.
The genetically engineered
mouse egg grows into an adult
mouse which will make the
glowing protein.
Transgenic Organisms
• Any organism that contains genes from a
different organism (traits not normally
found in that species) is a transgenic
organism.
Extended shelf-life tomato (Flavr-Savr)
Herbicide resistant soybean (Roundup Ready)
What are some possible uses of
genetic engineering?
•
•
•
•
•
•
Improving crops
Creating bacteria that can produce medicine
Increasing food supplies
Alternative energy sources
Human body parts for transplant
Preventing human diseases (gene therapy)
Improving Crops
• Crops may be improved by making them
resistant to certain factors, like insects,
drought, herbicides, or frost
• Crops may also be “improved” by
engineering them to produce things like
vitamins that are not normally found in the
species
Agriculture Transgenics On the Market
Insect resistant cotton – Bt toxin kills the
cotton boll worm
• transgene = Bt protein
Source: USDA
Insect resistant corn – Bt toxin kills the
European corn borer
• transgene = Bt protein Bt Corn
Normal
Transgenic
Herbicide resistant crops
Now: soybean, corn, canola
Coming: sugarbeet, lettuce, strawberry
alfalfa, potato, wheat (2005?)
• transgene = modified EPSP synthase or
phosphinothricin-N-acetyltransferase
Source: Monsanto
Virus resistance - papya resistant to
papaya ringspot virus
• transgene = virus coat protein
Fishy Strawberries- Making a frost resistant strawberry
1. Fish antifreeze
gene is inserted into
a plasmid.
The flounder is a fish that live
in icy seas. It has a gene that
stops it from freezing to death.
2. Plasmid with
gene is placed into
a bacterium.
Strawberries are soft fruits that
can easily be damaged by
frost.
3. The bacterium with the
flounder gene is used to
“infect” strawberry cells.
4. The infected
cells grow into a
frost-resistant
strawberry plant.
Strawberry
cell with
Antifreeze
gene
Can genetic engineering end malnutrition
and vitamin deficiencies?
• Golden rice is genetically modified to contain
large amounts of beta-carotene, which is
converted by the body into vitamin A
• Vitamin A is important to factor for good vision
(particularly night vision) and a strong immune
system.
• Many individuals in poor and underdeveloped
countries receive inadequate amounts of vitamin A
in their diets, leading to higher incidences of
blindness.
Creating bacteria that can
produce medicine
• As you saw in a previous example, bacteria
have already been engineered to produce insulin
proteins that can be injected by human diabetics
to control their diabetes.
• Some other examples:
– Bacteria produce human growth hormone to treat
types of dwarfism
– Producing interferon for cancer treatments
Increasing Food Supplies
• In many parts of the world, hunger is
rampant due to limited food resources.
• One possibility is to produce fish species
that mature more quickly so that they can
breed and create new generations sooner.
Salmon
http://fish.dnr.cornell.edu/nyfish/Salmonidae/salmonidae.html
Alternative Energy Sources
• Fossil fuels are dwindling
• Ethanol (the current alternative) comes
mostly from corn, which is used as a major
food crop in most countries
• It would be most beneficial to use “waste”
and “leftovers” for fuel.
http://www.teachersdomain.org/resource/biot09.sci.engin.systems.ethanol/
Creating Human Body Parts for Transplant
• Individuals in need of an organ transplant
can often wait years for a donor organ.
• Organs from other species is not usually an
option because the immune system attacks
such transplants as “foreign”.
• Scientists are researching the possibility of
inserting human genes into other species so
that they can grow “human” organs for
transplant.
What’s Going On Here?
Photo of mouse growing a "human
ear" - a shape made of cartilage
Some Other Possibilities
• Earlier this decade, scientists at the
University of Minnesota created pigs that
pumped human blood (specifically human
hemoglobin)
Preventing and Curing Human Diseases
• Several human diseases (like cystic fibrosis
or breast cancer) have a genetic component.
• Individuals with these disorders have a
mutation, or mistake, somewhere in their
DNA sequence
• Replacing these mutated sequences with
“normal” sequences should fix the problem
• This process is known as gene therapy.
What is Gene Therapy?
1. Individuals with cystic fibrosis
have a faulty gene.
Patient’s cell
Patient’s DNA
2. To fix the problem, a copy of
the same gene from a healthy
person is spliced into a virus.
3. The patient’s lungs are infected
with the virus. It delivers the
working gene into the patient’s
cells. The cells can then make
the right protein, and the
patient can breathe normally.
Faulty Gene
Virus DNA
New working
gene
Patient’s DNA
Virus DNA with
new gene
Will We Be Able To Cure Cancer
With Gene Therapy?
Cancer happens when body cells grow out of
control. Scientists have found a gene called p53 which normally keeps cells under control.
Some individuals with cancer may have a nonworking copy of p-53. Experts are now looking
for a way to cure cancer by modifying faulty
DNA to make the p-53 gene work.
Lung cancer cells (530x). These cells are
from a tumor located in the alveolus (air sac)
of a lung.
Breast Cancer
What Else?
Using the jellyfish
protein to make a
naturally glowing
Christmas tree!
Adding a gene
from insect killing
bacteria to cotton
so that insects who
eat cotton will be
poisoned!
Genetically
engineered moths
that pass on deadly
disease genes to
their relatives so
they die and won’t
be able to destroy
crops!
A gene from a spider
has been inserted
into some goats.
Their milk now
contains tiny strands
of spider silk which
can be made into a
strong, stretchy
rope.