Download Bioethics Lesson Plan

Lecture on Chapter 11-Gene
Technology
(Transparencies 39, 40, 31 A,
32A, 33A, 43 A and 41)
11-1 Genetic Engineering in
Medicine and Society
Describe four basic steps
commonly used in genetic
engineering experiments.
Genetic Engineering- is the
process of manipulating genes
for a practical purpose.
Genetic engineering involves
Recombinant DNA- DNA made
from two or more different
organisms.
Vector-an agent that is used to
carry the gene of interest into
another cell (viruses, yeast or
plasmids).
Plasmids- circular DNA
molecules that can replicate
independently of the main
chromosomes of bacteria.
Step 1- Cutting the DNA
containing the gene of interest
(human insulin gene) and the
DNA from a vector with
restrictive enzymes (EcoRI).
Step 2- Making recombinant
DNA. The fragments of human
insulin DNA and fragments of
the vector are combined. An
enzyme called DNA ligase is
added to help the loose ends of
DNA stick together to create
recombinant DNA. The
recombinant DNA is inserted
into the bacteria.
Step 3- Cloning. The human
insulin gene is cloned when
bacteria are allowed to
reproduce.
Step 4- Cells are screened to
isolate those cells in which the
gene of interest has been
successfully inserted. One way
to screen for the cloned bacteria
is to add a gene for tetracycline
resistance with the insulin gene.
The bacterial cells that take up
the recombined plasmids are
identified by adding the
antibiotic tetracycline to the
bacterial cultures. Only the
recombinant bacteria (have the
insulin gene and the tetracycline
resistance) are resistant to the
antibiotic and survive.
\
Evaluate how restriction
enzymes are used in genetic
engineering.
Restrictive enzyme- bacterial
enzymes that recognize and bind
to specific short sequences of
DNA, and then cut the DNA
between specific nucleotides
within the sequences. (Fig 11-3)
 Each enzyme recognizes a
specific nucleotide sequence.
 Usually the sequence is a
palindrome, meaning it reads
the same backwards and
forward like the word “boob,”
“Bob” or “mom.”
 The cuts of most restrictive
enzymes leave short single
strands of DNA on the ends
that are complimentary to each
other like AATT and TTAA.
These ends are called “sticky
ends.”
 With the help of DNA ligase
(enzyme) the two DNA
molecules bonds together at
the sticky ends by means of
complementary base pairing.
Relate the role of
electrophoresis and probes in
identifying a specific gene.
The surviving bacterial colonies
are tested for the presence of
cloned genes (insulin gene). One
method to test for the presence of
a cloned gene is called a
Southern Blot test.
Southern Blot Test
Step 1- The DNA from each
bacterial clone colony is
isolated and cut into fragments
by restrictive enzymes.
Step 2- DNA fragments are
separated by gel
electrophoresis (Fig 11-5), a
technique that uses an electrical
charge within a rectangle of gel
to separate molecules by their
size and charge. The DNA is
negatively charged, it migrates
towards the positive pole where
the electric charge is applied.
The small DNA fragments move
the fastest through the gel. A
pattern of bands is formed. The
gel is soaked in a chemical
solution that separates the double
strands in each DNA fragment.
Step 3- The DNA is transferred
to filter paper (blotted). A
probe is added. Probes- are
radioactive or florescent-labeled
RNA on single-stranded DAN
pieces that are complementary to
the gene of interest.
Step 4- Only DNA fragments
that contain the gene of interest
bind to probes.
11-2 Genetic Engineering in
Medicine and Society
Describe how drugs produced
by genetic engineering are
being used.
Many genetic disorders occur
when a person’s body fails to
produce a critical protein.
Therefore large amounts of these
proteins are needed to treat
person will various genetic
illnesses and genetic engineering
provides a fast way to do this.
Examples
Anticoagulants (Used in heart
attack patients)- proteins that
dissolve blood clots
Factor VIII (Treat Hemophilia
patients)- protein that promotes
blood clotting
Insulin (Treat Diabetes patients)a hormone that lowers blood
glucose levels
Summarize the steps involved
in making a genetically
engineered vaccine.
Traditional vaccines are solutions
containing all or part of a
harmless version of a pathogen.
When a vaccine is injected into a
human, the immune system
recognizes the pathogen’s
surface proteins and responds by
making defensive proteins called
antibodies. In the future, if the
same pathogen enters that same
person, the antibodies are there to
combat and stop its growth
before it can cause disease. The
danger is that if the pathogen is
not killed or weakened when
preparing the vaccine a person
my get sick with the very disease
they were trying to protect
themselves from.
In Genetically engineered
vaccines there is not the danger
of infecting the person with the
disease because the gene that
codes for the surface proteins of
the harmful bacteria or virus
(pathogen) can be inserted into
the DNA of a harmless bacteria.
The body recognizes the surface
proteins and still makes
antibodies. In the future if the
real pathogen enters the body, the
antibodies recognize its surface
proteins and attack it before it
can cause the disease.
Describe how gene therapy is
being used to try to cure
genetic disorders.
Gene Therapy is a technique that
involves putting a healthy copy
of a gene into the cells of a
person whose copy of the gene is
defective.
Many genetic disorders occur
when an individual lacks a
functioning copy of a particular
gene. There are about 4,000
identified human genetic
disorders.
Gene Therapy Examples
Cancer researchers identified a
naturally occurring protein in
white blood cells that attack and
kills cancer called tumor necrosis
factor (TNF). However this
seems to rarely happen in the
human body. Therefore
researchers genetically modified
white blood that more effective
use TNF and they are injected
into people who have cancer.
Cystic Fibrosis researchers are
working on nasal sprays that
carry the normal gene that a
person with Cystic Fibrosis
lacks.
Ultimately researchers are
working towards finding
permanent replace defective
genes with good genes.
However, there are many
obstacles including how and
where to insert genes safely and
directly into cells.
Identify different uses for DNA
fingerprints
 Other than identical twins, no
two individuals have the same
genetic material. Thus every
person (except identical twins)
has a unique DNA fingerprint.
 DNA fingerprints are used to
identify organisms
 Identify the parents of child
 Identify a rapist or murder in a
criminal case
 DNA fingerprint technique is
very to a Southern Blot test.
Summarize two major goals of
the Human Genome Project.
(Watch CNN video and read
“Secrets of Your Genes” on
page 245-247.)
 Determine the nucleotide
sequence of the entire human
genome
 To map the location of every
gene on each chromosome by
the year 2003 or sooner.
The controversy of the Human
Genome Project has been over
the “ownership” of the human
genome information. If a few
private companies own the
information and charge a fee for
its use then it may substantially
slow research to find the cure to
gene disorders.
11-3 Genetic Engineering in
Agriculture
Describe ways in which gene
engineering has been used to
improve plants.
 More tolerant to soils, climate
and the environment
 Control how fast fruits ripen
 Increase nutritional value of
plants
 Make crops resistant to
weedkiller
 Make crops resistant to insects
(insert insecticide gene into
plant DNA)
Summarize ways in which
genetic engineering techniques
have been used to modify farm
animals.
 Add growth hormones to
increase cow milk production
 Add extra copies of growth
hormone gene to increase the
weigh of cows and hogs
 Genetically modify farm
animals so they produce
human proteins for medical
purposes.
Animals that have foreign DNA
are called Transgenic Animals.
Summarize the cloning of
sheep through the use of
differentiated cells.
Differentiated cells- cell that has
become specialized to become a
specific type of cell (liver cell).
1997, Ian Wilmut announced he
had cloned a sheep named Dolly.
Dolly was born July 5, 1996.
(Fig 11-11) How was Dolly
cloned?
A lamb was cloned from the
nucleus of a mammary cell
(differentiated cells) taken from
an adult sheep. Previously,
scientists thought that cloning
could only happen using cells
embryonic or fetal cells that have
not differentiated.
Step1- Mammary cells were
extracted and grown in nutrient
deficient solution to stop the cell
cycle.
Step 2- Eggs cells were extracted
and the nucleus from each was
removed.
Step3- A mammory cell was
placed next to the “empty” egg
cell. An electric shock opened
the cell membranes so that the
cells fused and division was
triggered.
Step 4- The embryo developed in
vitro and later was implanted into
a surrogate mother.
Step 5- Dolly was born.
For More Information:
“Ewe Again? Cloning from
Adult DNA” Science News,
March 1, 1997, vol. 151, p. 132.
Human Genome Project
Information.
http://www.ornl.gov/TechReso
urces/Human_Genome/home.h
tml
Biotechnology Information
http://www.nal.usda.gov/bic/
National Human Genome
Research Institute (NHGRI)
http://www.nhgri.nih.gov/index
.html
Beardsley, Tim. “An Express
Route to the Genome?”
Scientific American, August
1998, 30-32.
Shreeve, James. “Secrets of
the Gene.” National
Geographic, October 1999, 4275.
Thompson, Dick. “Gene
Maverick.” Time, January 11,
1999, 54-55.