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DNA Technology Notes
Genetic Engineering – making changes
in the DNA code
DNA Manipulation:
1. Cells are opened and the DNA is
separated from other cell parts
2. Biologists cut the DNA into smaller
fragments using restriction
enzymes which cut the DNA at a
specific sequence of nucleotides
Gel Electrophoresis
3. Using gel electrophoresis, a mixture of DNA
fragments is placed at one end of a porous
gel. When electric voltage is applied, DNA
(negatively charged) move toward the positive
end of the gel. The smaller the DNA fragment,
the faster and farther it moves!
DNA fingerprinting
Can you determine
who the father is?
CSI: Who is the Dad?
Can you determine
who the father is?
DNA Fingerprinting and Endangered
Species
• DNA can identify endangered or protected
animals.
• The DNA from endangered animals has been
preserved in banks.
• For example, DNA from grizzly bears has been
banked to help these declining animals
preserve a healthy genetic pool.
Cell Transformation- Transforming
Bacteria (recombinant DNA)
During transformation, a cell takes in DNA from
outside the cell. This external DNA becomes a
component of the cell’s DNA.
Plasmid
Plasmid
+ DNA
Bacterium
Transformed
Bacterium
Free DNA
Cell Transformation
In bacteria, the circular DNA molecule is known
as a plasmid.
Plasmid DNA has two essential features:
1. Its DNA sequence helps promote plasmid
replication.
2. If the plasmid containing the foreign DNA
manages to get inside a bacterial cell, this
sequence ensures that it will be replicated.
Bacterial Transformation
Why is Transforming Bacteria
Important?
When organisms contains genes from another
species, they are called transgenic.
Transgenic bacteria now produce important
substances useful for health and industry.
These transformed bacteria produce proteins
cheaply, quickly, and abundantly.
Examples are human insulin for people with
diabetes, growth hormones and clotting
factor for people with hemophilia.
Examples of Other Transgenic Organisms
(Genetically Modified Organisms):
Transgenic Animals- laboratory mice have been
produced with human genes to that their
immune systems are similar to humans. This
way scientists can study human diseases by
using mice. Some livestock have extra copies
of growth hormone genes which allows them
to grow faster and have leaner meat.
Gene causes these mice to glow in the dark. Normally,
the gene is found in jellyfish.
How Did They Do
That?
Jellyfish cell
1.
Virus
Virus
inserting their
DNA into a
cell
2.
3.
Mouse
cell
4.
5.
The jellyfish has a gene that makes a
glowing protein. This makes the
jellyfish glow in some types of light.
The glowing gene is taken from a
jellyfish cell and spliced (inserted)
into an empty virus cell (with no bad
virus in it)
The genetically engineered virus
attaches itself to the fertilized mouse
egg cell.
The virus delivers the glowing gene
into the egg cell nucleus, where it
joins the mouse DNA.
The genetically engineered mouse
egg grows into an adult mouse which
will make the glowing protein. The
glow is too faint to see under normal
lights but can be detected using a
special camera.
What’s Been Done So Far?
• Genetically engineering
chickens so they have no
feathers – why?
• Genetically engineering mice
so they have no fur – why?
• Genetically engineering
salmon (fish) so they grow
much faster than normal
salmon – why?
http://www.exn.ca/Stories/20
00/04/11/61.asp
• Glowing mice
Examples of Other Transgenic
Organisms (GMO’s):
Transgenic Plants
Plants can contain genes that produce a natural
insecticide so that plants do not have to be
sprayed.
In the future, plants could produced human
antibodies to help fight diseases.
1. The
flounder’s
antifreeze gene
is copied and
inserted into a
small ring of
DNA taken from
a bacteria cell.
This diagram shows how one
type of GM food, a strawberry
that resists frost damage is
made.
The flounder is a fish that live in
icy seas. It has a gene that stops
it from freezing to
death.Strawberries are soft fruits
that can easily be damaged by
frost.
2. The DNA ring
containing the
flounder gene is put
into a second
bacterium.
3. This second bacterium is
used to infect the strawberry
cell. The flounder’s antifreeze
gene enters the strawberry’s
DNA.
4. The new GM
strawberry cell is
grown into a GM
strawberry plant
which can be bred
many times.
Strawberry cell
with Antifreeze
gene
Wonder
what they
used to
make this
one
green!
Thanks to the new gene, GM strawberries make
a protein which helps them resist frost. They
don’t contain any other fish genes and, and do
not taste or smell of fish.
Examples of Other Transgenic
Organisms:
A rice plant has been developed to contain
vitamin A, a nutrient that is essential for our
health. Rice is a major food source for billions
of the world’s population
What Have I Eaten?
GMO food list
Genetically modified (GM) foods possess
specific traits such as tolerance to
herbicides or resistance to insects or
viruses.
By most estimates, up to 70% of the
processed foods at your local grocery
store contain at least one ingredient
that’s been genetically altered
Click
Genetically modified to travel
better so don’t have to be
picked when green – better
tasting!
Click
Genetically modified to
reduce being eaten by
insects.
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.
How can we use genetically
engineering to help us?
By inserting a gene for human insulin into an
E.Coli bacterium, the E. coli will make lots of
insulin, which scientists and doctors can collect
and use.
Right now, doctors are using pig hearts for
transplants but there are still rejection problems.
One day soon, scientists will be able to
genetically engineer pigs to grow human organs
for use in transplants.
Pros and Cons of GMO’s
Crops
• Better taste and quality
• Less time to ripen.
• More nutrients, more food, and stress tolerance
• Improved resistance to disease, pests, and
herbicides
• New products and growing techniques
Animals
• Increased resistance, productivity, hardiness, and
feed efficiency
• Better yields of meat, eggs, and milk
• Improved animal health and diagnostic methods
Environment
• "Friendly" bioherbicides and bioinsecticides
• Conservation of soil, water, and energy
• Better natural waste management
• More efficient processing
Society
• More food for growing populations
Safety
• Potential human health impact: allergens, transfer
of antibiotic resistance markers, unknown effects
• Potential environmental impact: unintended
transfer of transgenes through cross-pollination,
loss of flora and fauna biodiversity
Access and Intellectual Property
• Domination of world food production by a few
companies
• Increasing dependence on Industralized nations by
developing countries
Ethics
• Violation of natural organisms' intrinsic values
• Tampering with nature by mixing genes among
species
• Objections to consuming animal genes in plants and
vice versa
• Stress for animal
Labeling
• Not mandatory in some countries (e.g., U. States)
• Mixing GM crops with non-GM confounds labeling
attempts
Human Genome Project
• Started in 1990
• Research effort to sequence all of
our DNA (46 chromosomes)
• Over 3.3 billion nucleotides
• Mapping every gene location (loci)
• Conducted by scientists around the
world
23
Benefits of Human Genome Project
• Improvements in medical
prevention of disease, gene
therapies, diagnosis
techniques …
• Production of useful protein
products for use in medicine,
agriculture, bioremediation
and pharmaceutical
industries.
24
Gene Therapy
Gene Therapy- an absent or faulty gene is
replaced with a normal, working gene.
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Gene Therapy
In gene therapy, viruses are often used because
they have the ability to enter a cell’s DNA.
The virus particles are modified so that they
cannot cause disease. Then, a DNA fragment
containing a replacement gene is spliced to
the viral DNA.
Virus
Gene Therapy
The patient is then infected with the modified
virus particles, which should carry the gene
into cells to correct the genetic defects.
Unfortunately, these experiments have not been
very successful.
Gene therapy remains a high-risk, experimental
procedure.
Cystic Fibrosis and Gene Therapy
What is Gene Therapy?
1.
2.
3.
In people with cystic
fibrosis, one of the
genes is faulty and
cannot do its job
properly.
To fix the problem, a
copy of the same gene
from a healthy person
is spliced into a virus.
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.
Patient’s cell
Patient’s DNA
Faulty Gene
Virus DNA
New working
gene
Patient’s DNA
Virus DNA with
new gene
Severe Combined Immunodefiency
(aka “Bubble Boy”)
In 1990, SCID was the first
illness treated by gene therapy.
The normal gene was
transferred into the defective
white blood cells to compensate
for the genetic mutation.
Cloning
A clone is a member of a population of
genetically identical cells produced from a
single cell.
Researchers hope that cloning will enable them
to make copies of transgenic animals to help
save endangered species.
How to Clone a Sheep
Cloning a Human
Cloning
This technology is controversial because some
studies suggest that cloned animals may suffer
from genetic defects and health problems.
Cloning in humans raises serious ethical and
moral issues.
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