Download Genetic Engineering

What is biotechnology?
• The use of living organisms to do
practical tasks.
• Early examples:
– The use of microorganisms to make
cheese and wine
– Selective breeding of livestock and crops
– Production of antibiotics from
microorganisms
Selective Breeding
• Breed only those
plants or animals with
desirable traits
• People have been
using selective
breeding for 1000’s
of years with farm
crops and
domesticated
animals.
Genetically modified organisms are
called transgenic organisms.
TRANSGENIC ANIMALS
1.
Mice – used to study human
immune system
2.
Chickens – more resistant to
infections
3.
Cows – increase milk supply
and leaner meat
4. Goats, sheep and pigs –
produce human proteins in
their milk
Goal of biotechnology today:
• To find practical applications of DNA
techniques for the improvement of
human health and food production
– Making gene products using Genetic Engineering
– Medical uses. Diagnosis of disease
– Making vaccines and other pharmaceutical
products
– Forensic uses of DNA such as DNA fingerprinting
– Agricultural uses such as making transgenic
plants
DNA TECHNOLOGY
DNA recombination or genetic
engineering is the direct
manipulation of genes for practical
purposes
Recombinant DNA technology
• Refers to the set of techniques for
combining genes from different sources
in vitro( in a test tube) and transfering this
DNA into a cell so it can be expressed.
• These techniques were first developed
around 1975 and resulted in the
appearance of the Biotechnology
industry
– Researchers can insert desired genes into
plasmids, creating recombinant DNA
•
And insert those plasmids into bacteria
Bacterium
Cell containing gene
of interest
1 Plasmid
isolated
2 DNA
isolated
3 Gene inserted
into plasmid
Plasmid
Bacterial
chromosome
Recombinant DNA
(plasmid)
DNA
Gene of
4 Plasmid put into interest
bacterial cell
Recombinant
bacterium
5 Cell multiplies with
gene of interest
Copies of gene
Gene for pest
resistance
inserted into
plants
Figure 12.1
Copies of protein
Clone of cells
Gene used to alter bacteria
for cleaning up toxic waste
Protein used to
make snow form
at higher
temperature
Protein used to dissolve blood
clots in heart attack therapy
Genetic Engineering
• DNA from one
species is inserted
into another
species.
• Ex. Human Insulin
for diabetics is
now made by
bacteria cells!
•Therapeutic hormones
– In 1982, humulin, human insulin produced
by bacteria
•
Became the first recombinant drug
approved by the Food and Drug
Administration
Figure 12.7A
Restriction enzymes cut DNA at
specific sequences in the DNA
Restriction enzymes = scissors
Recombinant DNA
Two pieces of DNA cut
with the same restriction
enzyme will be able to
re-combine with each
other.
Plants
• 1) Examples of transgenic
plants with resistance to
viruses…
potatoes, tomatoes,
tobacco
• 2) Examples of transgenic
plants with resistance to
insects… corn, cotton
Animals
• Bacteria now produce all of
the following…
– Human growth hormone
(HGH) –
– Human insulin (replaced cow
and pig insulin for human therapy )
– Factor VIII (replaced clotting
factors taken from human blood.)
Electrophoresis
•
•
•
•
•
•
Separation of Negatively charged
DNA molecules in an electric field.
The DNA is cut by a restriction
enzyme into small pieces and
placed in each well of the agarose
gel.
The Negatively charged DNA
fragments will move toward the
positively charged end of the gel.
The larger and longer fragments
move slower than the smaller
shorter fragments.
This creates a pattern of DNA
fragments through the gel.
The gel is then stained to alllow
the DNA fragment pattern to be
seen. This pattern is called a
DNA Fingerprint.
Gel electrophoresis sorts DNA molecules
by size
Mixture of DNA
molecules of
different sizes
–
–
Longer
molecules
Power
source
Gel
+
Shorter
molecules
+
Figure 12.10
Completed gel
– After digestion by restriction enzymes
•
The fragments are run through a gel
1
–
2
Longer
fragments
z
x
w
Shorter
fragments
Figure 12.11B
+
y
y
Crime
• Forensic science is the use of scientific
knowledge in legal situations.
• The DNA profile of each individual is highly
specific.
• The chances of two people having exactly
the same DNA profile is 30,000 million to 1
(except for identical twins).
– DNA fingerprinting is a set of laboratory
procedures
•
•
That determines with near certainty whether two
samples of DNA are from the same individual
That has provided a powerful tool for crime
scene investigators
Investigator at one
of the crime scenes
(above), Narborough,
England (left)
Example
• A violent murder occurred.
• The forensics team retrieved a blood
sample from the crime scene.
• They prepared DNA profiles of the blood
sample, the victim and a suspect as
follows:
Does suspect DNA bands match
DNA from the crime scene?
Suspects
Profile
Blood sample
from crime
scene
Victims
profile
Solving Medical Problems
DNA profiles can be used to determine whether a
particular person is the parent of a child.
A childs paternity (father) and maternity(mother)
can be determined.
This information can be used in
• Paternity suits
• Inheritance cases
• Immigration cases
Example: A Paternity Test
• By comparing the DNA profile of a
mother and her child it is possible to
identify DNA fragments in the child
which are absent from the mother and
must therefore have been inherited
from the biological father.
Does this man’s DNA match the
DNA of the child?
Mother
Child
Man
What is cloning?
• Cloning is a process that can be used to
produce genetically identical copies of an
organism.
• Researchers have cloned many biological
materials, including genes, cell, and entire
organisms.
Do clones occur naturally?
• Yes. In nature, some
plants and singlecelled organisms,
such as bacteria,
produce genetically
identical offspring
through a process
called asexual
reproduction.
How are animals cloned?
• In reproductive cloning, researchers
remove a mature somatic cell, such as a
skin cell from an animal that they wish to
copy.
• Then transfer the DNA of the donor
animal's somatic cell into an egg cell, or
oocyte, that has had its own DNAcontaining nucleus removed.
• The DNA-containing nucleus is removed
from the somatic (body) cell and then
injected into an empty egg cell.
• An electrical current is used to fuse the
two and start the process of cell
division.(mitosis)
• The egg is allowed to develop into an
early-stage embryo in the test-tube and
then is implanted into the womb of an
adult female animal.
• Adult female gives birth to an animal that
has the same genetic make up as the
animal that donated the somatic cell.
What was Dolly?
• Dolly the sheep was successfully cloned
in Britain in 1996 by the scientist “Ian
Wilmut” and was put down in February
2003 after developing a lung infection
and arthritis.
• Dolly the sheep
became the first
vertebrate cloned from
the cell of an adult animal.
Human Genome Project
• Started 1988, finished 2001,
the entire sequence of bases
in human DNA is now known.
• This multi-national effort has
led to increased knowledge
of …
–
–
–
–
–
Human genetic diseases
Gene therapies
Evolutionary relationships
Cellular functions
Cancer genes