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Chapter 12
Biotechnology
Lectures by
Gregory Ahearn
University of North Florida
Copyright © 2009 Pearson Education, Inc..
12.1 What Is Biotechnology?
 Biotechnology is any use or alteration of
organisms, cells, or biological molecules to
achieve specific practical goals.
• Today, selective breeding is an important part
of biotechnology.
• Modern biotechnology frequently uses genetic
engineering.
• This term refers to direct methods for
modifying genetic material.
Copyright © 2009 Pearson Education Inc.
12.1 What Is Biotechnology?
 A key tool in genetic engineering is
recombinant DNA, which is DNA that has
been altered to contain genes or parts of
genes from different organisms.
• Large amounts of recombinant DNA can be
grown in bacteria, viruses, or yeasts, and then
transferred into other species.
• Plants or animals that express DNA that has
been modified or derived from other species
are called transgenic, or genetically modified,
organisms (GMOs).
Copyright © 2009 Pearson Education Inc.
12.1 What Is Biotechnology?
 Modern biotechnology also includes many
methods of manipulating DNA, whether or
not the DNA is subsequently put into a cell
or an organism.
 For example, determining the nucleotide
sequence of specific pieces of DNA is
crucial to forensic science and the diagnosis
of inherited disorders.
Copyright © 2009 Pearson Education Inc.
12.1 What Is Biotechnology?

This chapter is organized around five
themes.
1. Recombinant DNA mechanisms found in
nature
2. Biotechnology in criminal forensics (DNA
matching)
3. Biotechnology in agriculture, and production
of transgenic plants and animals
4. The Human Genome Project
5. Biotechnology in medicine; the treatment of
inherited disorders
Copyright © 2009 Pearson Education Inc.
12.2 How Does DNA Recombine In Nature?
 Many natural processes can transfer DNA
from one organism to another, sometimes
even to organisms of different species.
• Sexual reproduction recombines DNA from
two different organisms.
• Every egg and sperm contain recombinant
DNA, derived from the organism’s two
parents.
• When a sperm fertilizes an egg, the resulting
offspring also contains recombinant DNA.
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12.2 How Does DNA Recombine In Nature?
 Transformation may combine DNA from
different bacterial species.
• Bacteria can undergo several types of
recombination that allow gene transfer
between species.
• In a process called transformation, bacteria
pick up pieces of DNA from the environment.
• The DNA may be part of the chromosome of
another bacterium or from another species, or
may be in the form of tiny circular DNA
molecules called plasmids.
Copyright © 2009 Pearson Education Inc.
12.2 How Does DNA Recombine In Nature?
 Transformation in
bacteria
bacterial
chromosome
plasmid
1 micrometer
(a) Bacterium
bacterial
chromosome
bacterial
chromosome
plasmid
DNA
fragments
The plasmid replicates
in the cytoplasm
(c) Transformation with a plasmid
A DNA fragment is
incorporated into
the chromosome
(b) Transformation with a DNA fragment
Fig. 12-1
Copyright © 2009 Pearson Education Inc.
12.2 How Does DNA Recombine In Nature?
 Viruses may transfer DNA between species.
• Viruses are genetic material encased in a
protein coat, and they transfer their genetic
material to the host cells that they infect.
• Once inside a host cell, the viral genes
replicate and use the infected cell’s enzymes
and ribosomes to synthesize viral proteins.
• These proteins form new viruses that are
released to infect other cells.
Copyright © 2009 Pearson Education Inc.
12.2 How Does DNA Recombine In Nature?
 Viruses may transfer genes between cells.
virus
viral DNA
The virus enters
host
the host cell
cell
host cell DNA
A virus attaches to
a susceptible host cell
The virus releases its
DNA into the host cell;
some viral DNA (red) may
be incorporated into the
host cell’s DNA (blue)
viral DNA
“hybrid virus”
The host cell
bursts open, releasing
newly assembled
viruses; if “hybrid
viruses” infect a
second cell, they may
transfer genes from
the first cell to the
second cell
viral proteins
New viruses
assemble; some host
cell DNA is carried by
“hybrid viruses”
Viral genes encode
the synthesis of viral
proteins and viral gene
replication; some host
cell DNA may attach to
the replicated viral DNA
(red/blue combination)
Fig. 12-2
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12.2 How Does DNA Recombine In Nature?
PLAY
Animation—Genetic Recombination in Bacteria
Copyright © 2009 Pearson Education Inc.
12.3 How Is Biotechnology Used In
Forensic Science?
 The polymerase chain reaction (PCR)
amplifies DNA.
• PCR produces virtually unlimited amounts of
selected pieces of DNA.
• Primers (small pieces of complementary RNA)
tell the DNA polymerase where on the DNA
molecule to start copying.
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12.3 How Is Biotechnology Used In
Forensic Science?
 The polymerase chain reaction (PCR)
amplifies DNA (continued).
• One primer is complementary to the beginning
of the DNA strand to be copied.
• The other primer is complementary to the
other end, so DNA replication occurs in both
directions.
• PCR consists of the following steps repeated
as often as needed to make enough copies of
DNA.
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12.3 How Is Biotechnology Used In
Forensic Science?
 In a small test tube, DNA is mixed with
primers, free nucleotides, and a special
heat-resistant DNA polymerase.
1. The test tube is heated to 90°C, which
breaks the hydrogen bonds between
complementary bases, separating the DNA
into single strands.
2. The temperature is lowered to about 50°C to
allow the primers to form complementary
base pairs with the original DNA strands.
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12.3 How Is Biotechnology Used In
Forensic Science?
3. The temperature is raised to 70–72°C so
DNA polymerase can use the primers to
make copies of the DNA segment bounded
by the primers.
4. The cycle is repeated as many times as
desired.
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12.3 How Is Biotechnology Used In
Forensic Science?
 PCR copies a specific DNA sequence.
194°F (90°C) 122°F (50°C)
primers
original
DNA
161°F (72°C)
DNA
polymerase
Heating
Cooling allows
separates
primers and
DNA strands DNA polymerase
to bind
(a) One PCR cycle
new DNA
strands
New DNA
strands a
synthesized
Fig. 12-3a
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12.3 How Is Biotechnology Used In
Forensic Science?
DNA
fragment
to be
amplified
PCR
cycles
1
2
3
4 etc.
DNA
copies 1
2
4
8
16 etc.
(b) Each PCR cycle doubles the number of copies of the DNA
Fig. 12-3b
Copyright © 2009 Pearson Education Inc.
12.3 How Is Biotechnology Used In
Forensic Science?
 Differences in short tandem repeats can
identify individuals.
• In many criminal investigations, PCR is used
to amplify the DNA so that there is enough to
compare the DNA left at the crime scene with
the suspect’s DNA.
• Forensic experts have found that small
segments of DNA, called short tandem
repeats (STRs), can be used to identify people
with astonishing accuracy.
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12.3 How Is Biotechnology Used In
Forensic Science?
 Short tandem repeats
A T A T T T T G AA G A T A G A T A G A T A G A T A G A T A G A T A G A T A G A T A G G T A
T A T A AA A C T T C T AT C T AT C T A T C T AT C T A T C T AT C T A T C T A T C C A T
Eight side-by-side (tandem) repeats
of the same four-nucleotide sequence
AG A T
TC TA
Fig. 12-4
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12.3 How Is Biotechnology Used In
Forensic Science?
 Differences in short tandem repeats can
identify individuals (continued).
• People have different numbers of repeated
nucleotides in their STRs.
• A perfect match of 10 STRs in a suspect’s
DNA and the DNA found at a crime scene
means that there is less than one chance in a
trillion that the two DNA samples did not come
from the same person.
Copyright © 2009 Pearson Education Inc.
12.3 How Is Biotechnology Used In
Forensic Science?
 Gel electrophoresis separates DNA segments.
• A mixture of DNA pieces is separated by a technique
called gel electrophoresis.
• The mixture of DNA is loaded onto a slab of agarose.
• The gel is put in a chamber with electrodes connected
to each end; one is positive, the other negative.
• Current is allowed to flow between the electrodes
through the gel.
• The flowing current separates the DNA fragments,
forming distinct bands on the gel.
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12.3 How Is Biotechnology Used In
Forensic Science?
 Gel electrophoresis
DNA samples are pipetted
into wells (shallow slots) in the
gel. Electrical current is sent
through the gel (negative at the
end with the wells, positive at
the opposite end).
power supply
pipetter
gel
wells
Fig. 12-5(1)
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12.3 How Is Biotechnology Used In
Forensic Science?
 Gel electrophoresis (continued)
Electrical current moves the
DNA segments through the gel.
Smaller pieces of DNA move
farther toward the positive
electrode.
DNA “bands”
(not yet
visible)
Fig. 12-5(2)
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12.3 How Is Biotechnology Used In
Forensic Science?
 DNA probes are used to label specific
nucleotide sequences.
• Unfortunately, the DNA bands are invisible, so
how can anyone identify which band contains
a specific STR?
• Usually, the two strands of the DNA double
helix are separated during gel electrophoresis.
• This allows pieces of synthetic DNA, called
DNA probes, to base-pair with specific DNA
fragments in the sample.
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12.3 How Is Biotechnology Used In
Forensic Science?
 The DNA probes are labeled, either by
radioactivity or by attaching colored
molecules to them.
 A given DNA probe will only label certain
DNA sequences and not others.
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12.3 How Is Biotechnology Used In
Forensic Science?
 DNA probes identify
label
(colored molecule)
specific DNA
probe
sequences.
TC T ATCT ATC T A
T T T GA AG A T AG A T AG A T
STR #1: The probe base-pairs and binds
to the DNA
TC TATCT ATC T A
AC T GAAT G A A T G A A T G A A T G
STR #2: The probe cannot base-pair with the DNA,
so it does not bind
Fig. 12-6
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12.3 How Is Biotechnology Used In
Forensic Science?
 DNA probes are used to label specific
nucleotide sequences (continued).
• The single-stranded DNA segments are
transferred out of the gel and onto a piece of
nylon paper.
• The paper is next bathed in a solution
containing a specific DNA probe that will basepair with, and bind to, only a specific STR,
making this STR visible.
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12.3 How Is Biotechnology Used In
Forensic Science?
 Gel electrophoresis (continued)
The gel is placed on special
nylon “paper.” Electrical current
drives the DNA out of the gel
onto the nylon.
gel
nylon
paper
Fig. 12-5(3)
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12.3 How Is Biotechnology Used In
Forensic Science?
 Gel electrophoresis (continued)
The nylon paper with the
DNA bound to it is bathed in a
solution of labeled DNA probes
(red) that are complementary to
specific DNA segments in the
original DNA sample.
solution of
DNA probes
(red)
nylon
paper
Fig. 12-5(4)
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12.3 How Is Biotechnology Used In
Forensic Science?
 Gel electrophoresis (continued)
Complementary DNA
segments are labeled by the
probes (red bands).
Fig. 12-5(5)
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12.3 How Is Biotechnology Used In
Forensic Science?
 Every person has a unique DNA profile.
• In the early 1990s, forensic scientists ran DNA
samples from a crime scene and from the suspects
side-by-side on a gel, to see which suspect’s DNA
matched that found at the scene.
• In modern STR analysis, a suspect and crime scene
DNA samples can be run on different gels in different
locations.
• The reason is that people have different numbers of
repeats of their STRs, so that every person on
Earth—except for identical twins—has a unique set of
STRs.
Copyright © 2009 Pearson Education Inc.
STR
name
Penta D
CSF
D16
Number of repeats
12.3 How Is Biotechnology Used In
Forensic Science?
 When DNA samples are run on STR gels,
they produce a pattern, called a DNA profile
D16: An STR on chromosome 16
15
14
13
12
11
10
9
8
DNA samples from
13 different people
D7
Fig. 12-7
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12.3 How Is Biotechnology Used In
Forensic Science?
 Every person has a unique DNA profile.
• Anyone convicted of certain crimes must give
a blood sample.
• Forensic technicians then determine the
criminal’s DNA profile.
• This DNA profile is coded and stored in
computer files.
• Because all forensic labs use the same STRs,
computers can easily determine if DNA left at
a crime scene matches one of the millions of
profiles stored in a profile database.
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12.4 How Is Biotechnology Used In
Agriculture?
 Many crops are genetically modified.
• Many herbicides kill plants by inhibiting an enzyme that
is used by plants, but not animals, to synthesize
essential amino acids.
• Many herbicide-resistant transgenic crops have been
given a bacterial gene encoding an enyzme that
functions even in the presence of these herbicides.
• These plants continue to synthesize normal amounts of
amino acid and proteins.
• Less competition from weeds—which are killed by the
herbicide, but not the crops—provides larger harvests.
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12.4 How Is Biotechnology Used In
Agriculture?
 Many crops are genetically modified
(continued).
• Insect resistance of many crops is enhanced
by giving them a gene, called Bt, from the
bacterium, Bacillus thuringiensis.
• The protein encoded by the Bt gene damages
the digestive tract of insects, but not
mammals.
• Bt crops therefore suffer less damage from
insects, and farmers have to apply less
pesticide to their fields.
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12.4 How Is Biotechnology Used In
Agriculture?
 How would a seed company make insectresistant Bt plants?
1. The desired gene is cloned.
2. First, one must obtain the gene; then, it must
be inserted into a plasmid so that huge
numbers of copies can be made.
3. Restriction enzymes cut the DNA at specific
nucleotide sequences.
4. Genes are inserted into plasmids through
the action of restriction enzymes isolated
from bacteria.
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12.4 How Is Biotechnology Used In
Agriculture?
5. Each restriction enzyme cuts DNA at a
specific nucleotide sequence.
EcoRI restriction enzyme
doublestranded
DNA
. . .AA T T G C T TAG A AT T C G A T T T G. . .
. . . T T AA C G A AT C T T A A G C T A AA C . . .
A specific restriction enzyme (EcoRI) binds
to the GAATTC sequence and cuts the DNA,
creating DNA fragments with “sticky ends.”
. . .A A T T G C T T A G
. . .T TA A C GA AT C T TAA
A A T T C G A T T T G. . .
G C T A A A C. . .
single-stranded
“sticky ends”
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Fig. 12-8
12.4 How Is Biotechnology Used In
Agriculture?
6. Cutting two pieces of DNA with the same
restriction enzyme allows the pieces to be
joined together.
7. The Bt gene is inserted into a plasmid by
cutting the DNA on either side of the Bt gene
and splitting open the circle of the plasmid
with the same restriction enzyme.
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12.4 How Is Biotechnology Used In
Agriculture?
DNA including Bt gene (blue)
plasmid
The DNA containing the Bt gene and the
plasmid are cut with the same restriction enzyme.
Fig. 12-9
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12.4 How Is Biotechnology Used In
Agriculture?
8. As a result, the ends of the Bt gene and the
opened-up plasmid both have
complementary bases in their ends, and can
base-pair with each other.
9. When the cut Bt genes and plasmids are
mixed together, some of the Bt genes will be
temporarily inserted between the ends of the
plasmid.
10. Adding DNA ligase permanently bonds the
Bt genes into the plasmid.
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12.4 How Is Biotechnology Used In
Agriculture?
recombinant
plasmid with
Bt gene
Bt genes and plasmids, both with the same
complementary sticky ends, are mixed together;
DNA ligase bonds the Bt genes into the plasmids.
Fig. 12-9(2)
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12.4 How Is Biotechnology Used In
Agriculture?
11. Plasmid-transformed bacteria insert the Bt
gene into a plant.
12. Certain bacteria can enter the cells of
specific types of plants.
13. These bacteria are transformed with the
recombinant plasmids.
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12.4 How Is Biotechnology Used In
Agriculture?
bacterium
bacterial
chromosome
recombinant
plasmids
Bacteria are transformed with the recombinant plasmids.
Fig. 12-9(3)
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12.4 How Is Biotechnology Used In
Agriculture?
14. When the transformed bacteria enter a plant
cell, the plasmids insert their DNA, including
the Bt gene, into the plant’s chromosomes.
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12.4 How Is Biotechnology Used In
Agriculture?
plant chromosome
plant cell
Bt gene
Transgenic bacteria enter the plant cells, and Bt genes
are inserted into the chromosomes of the plant cells.
Fig. 12-9(4)
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12.4 How Is Biotechnology Used In
Agriculture?
15. Therefore, any time that a plant cell divides,
all of its daughter cells inherit the Bt gene.
16. Hormones stimulate the transgenic plant
cells to divide and differentiate into entire
plants.
17. These plants are bred to one another, or to
other plants, to create commercially valuable
plants that resist insect attack.
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12.4 How Is Biotechnology Used In
Agriculture?
 Bt plants resist insect attack.
Fig. 12-10
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12.4 How Is Biotechnology Used In
Agriculture?
 Genetically modified plants may produce
medicines.
• Similar techniques can be used to insert
medically useful genes into plants, producing
medicines.
• Plants could be made to produce human
antibodies that would combat various
diseases.
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12.4 How Is Biotechnology Used In
Agriculture?
 Genetically modified plants may produce
medicines (continued).
• A direct injection of plant-produced antibodies
soon after infection might cure the resulting
disease much more rapidly than waiting for
the immune system to handle the pathogens.
• Plant-derived antibodies against bacteria that
cause tooth decay and non-Hodgkins
lymphoma could be produced cheaply,
enhancing the availability of therapies.
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12.4 How Is Biotechnology Used In
Agriculture?
 Genetically modified animals may be useful
in agriculture and medicine.
• Making transgenic animals involves injecting
the desired DNA into a fertilized egg, which is
then implanted into a surrogate mother.
• If the offspring are healthy and express the
foreign gene, they are then bred together to
produce homozygous transgenic organisms.
• Companies have developed salmon and trout
with modified or added growth-hormone
genes, which make the fish grow much faster
than wild fish.
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12.4 How Is Biotechnology Used In
Agriculture?
 Genetically modified animals may be useful
in agriculture and medicine (continued).
• Because medicines are generally more
valuable than meat, many researchers are
developing animals that will produce
medicines.
• Alpha-1-antitrypsin: a protein that may
prove value in treating cystic fibrosis
• Erythropoietin: a hormone that stimulates
red blood cell production
• Clotting factors for treating hemophilia
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12.5 How Is Biotechnology Used To Learn
About The Human Genome?
 In 1990, the Human Genome Project was
launched to determine the nucleotide
sequence of all DNA in our entire set of
genes, called the human genome.
• The human genome contains only about
21,000 genes comprising only 2% of the DNA.
• It is not known what the 98% of the remaining
DNA does.
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12.5 How Is Biotechnology Used To Learn
About The Human Genome?
 Knowing the human genome will help:
• Find out what many unknown proteins do.
• Understand human disease.
• Diagnose genetic disorders and devise
treatments or cures.
• Comparing the human genome to that of other
organisms will help us understand our place in
the evolution of life.
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12.6 How Is Biotechnology Used For
Medical Diagnosis And Treatment?
 DNA technology can be used to diagnose
inherited disorders.
• People inherit a genetic disease because they
inherit one or more dysfunctional alleles.
• Defective alleles have different nucleotide
sequences than functional alleles.
• Two methods are currently used to find out if a
person carries a normal allele or a
malfunctioning allele.
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12.6 How Is Biotechnology Used For
Medical Diagnosis And Treatment?
 Restriction enzymes may cut different
alleles at different locations.
• A defective allele may be cut by a particular
restriction enzyme, while a functional allele will
not.
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12.6 How Is Biotechnology Used For
Medical Diagnosis And Treatment?
 Diagnosing sickle-cell anemia with
restriction enzymes
MstII
cut #1
MstII
cut #2
MstII
cut #3
DNA probe
large piece
small piece
of DNA
of DNA
(a) MstII cuts the normal globin allele into two pieces
that can be labeled by a probe
Fig. 12-11a
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12.6 How Is Biotechnology Used For
Medical Diagnosis And Treatment?
 Diagnosing sickle-cell anemia with
restriction enzymes (continued)
MstII
cut #1
MstII
cut #3
DNA probe
very large piece
of DNA
(b)MstII cuts the sickle-cell allele into one very large
piece that can be labeled by the same probe
Fig. 12-11b
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12.6 How Is Biotechnology Used For
Medical Diagnosis And Treatment?
 Diagnosing sickle-cell anemia with
restriction enzymes (continued)
larger pieces
of DNA
smaller pieces
of DNA
Homozygous normal:
one band of large DNA
pieces and one band
of small DNA pieces
Homozygous
sickle-cell: one
band of very
large DNA
pieces
Heterozygous:
three bands
(c) Analysis of globin alleles by gel electrophoresis
Fig. 12-11c
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12.6 How Is Biotechnology Used For
Medical Diagnosis And Treatment?
 Different alleles bind to different DNA
probes.
• This method has been applied to
characterizing the 1,000 different CFTR (cystic
fibrosis) protein alleles.
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12.6 How Is Biotechnology Used For
Medical Diagnosis And Treatment?
 A cystic fibrosis diagnostic array
DNA probe
for normal
CFTR allele
DNA probes for
10 different mutant
CFTR alleles
(a) Linear array of probes for cystic fibrosis
colored molecule
A T C A T C T T T GG T G
piece of patient’s
DNA
(b) CFTR allele labeled with a colored
molecule
Fig. 12-12a,b
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12.6 How Is Biotechnology Used For
Medical Diagnosis And Treatment?
#1
Homozygous for normal CFTR alleles—
the person is phenotypically normal
#2
One normal and one defective CFTR allele—
the person is phenotypically normal
#3
Two different defective CFTR alleles—
the person develops cystic fibrosis
(c) Linear arrays with labeled DNA samples
from three different people
Fig. 12-12c
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12.6 How Is Biotechnology Used For
Medical Diagnosis And Treatment?
 Someday, physicians may be able to use an
array containing hundreds or thousands of
DNA probes for hundreds of disease-related
alleles.
 This will help them determine the
susceptibility for the diseases that each
patient has, and to tailor the patient’s
medical care accordingly.
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12.6 How Is Biotechnology Used For
Medical Diagnosis And Treatment?
 Arrays containing probes for thousands of
human genes are already manufactured.
 These arrays can be tailored to investigate
gene activity in specific diseases, such as
breast cancer.
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12.6 How Is Biotechnology Used For
Medical Diagnosis And Treatment?
 A human DNA microarray
Fig. 12-13
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12.6 How Is Biotechnology Used For
Medical Diagnosis And Treatment?
 DNA technology can be used to treat
disease.
• Thanks to recombinant DNA technology,
several medically important proteins are now
routinely made in bacteria.
• These proteins may prevent or cure a variety
of diseases, but they cannot cure inherited
disorders—they only treat symptoms.
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12.6 How Is Biotechnology Used For
Medical Diagnosis And Treatment?
 Biotechnology may be able to treat inherited
disorders in the future.
• Patients with defective CFTR proteins in their
lung cells can have viruses containing normal
CFTR alleles sprayed into their nose.
• The viruses enter the lung cells, and the
normal CFTR allele directs the synthesis of
normal CFTR protein.
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12.6 How Is Biotechnology Used For
Medical Diagnosis And Treatment?
 Using biotechnology to cure severe
combined immune deficiency (SCID)
• In the body, new cells are produced from stem
cells that can differentiate into several
possible cell types.
• SCID is a rare, inherited disorder in which a
child fails to develop an immune system; most
die before their first birthday.
• This disorder is due to a defective allele that
does not produce an enzyme called
adenosine deaminase.
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12.6 How Is Biotechnology Used For
Medical Diagnosis And Treatment?
 Using biotechnology to cure severe
combined immune deficiency (SCID)
(continued)
• A 4-year old patient had her white blood cells
treated with a virus containing a functional
allele, and these cells were returned to her
body.
• Now an adult, she has a normally functioning
immune system but must receive continual
injections of new treated white cells, since the
original treated white cells have died off.
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12.7 What Are Some Of The Major Ethical
Issues Of Modern Biotechnology?
 Should genetically modified organisms
(GMOs) be permitted in agriculture?
• Even though transgenic crops offer clear
advantages to farmers, many people
strenuously object to transgenic crops or
livestock.
• They fear that they may be hazardous to
human health or dangerous to the
environment.
Copyright © 2009 Pearson Education Inc.
12.7 What Are Some Of The Major Ethical
Issues Of Modern Biotechnology?
 Should genetically modified organisms
(GMOs) be permitted in agriculture?
(continued)
• In most cases, there is no reason to think that
GMO foods are dangerous to eat.
• The Bt protein is not toxic to mammals, and
should not prove a danger to human health.
• However, some people might be allergic to
genetically modified plants.
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12.7 What Are Some Of The Major Ethical
Issues Of Modern Biotechnology?
 Should genetically modified organisms
(GMOs) be permitted in agriculture?
(continued)
• A plant made transgenic by the incorporation
of a new gene may confer upon the crop a
trait that induces allergic reactions in some
people.
• In 2003, the U.S. Society of Toxicology studied
the risks of genetically modified plants and
concluded that the current transgenic plants
pose no dangers to human health.
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12.7 What Are Some Of The Major Ethical
Issues Of Modern Biotechnology?
 Are GMOs hazardous to the environment?
• Bt genes used in rice fields to add herbicide
resistance to the rice may escape in the pollen
and enter plants far away from the rice it was
intended to control.
• The plants receiving the unintentional genes
may then also obtain herbicide resistance.
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12.7 What Are Some Of The Major Ethical
Issues Of Modern Biotechnology?
 Are GMOs hazardous to the environment?
(continued)
• If these plants are weeds, they will become
resistant to control by the herbicides and will
negatively affect the rice crops.
• In 2002, a committee of the U.S. National
Academy of Sciences recommended more
thorough screening of transgenic plants before
they are used commercially, and sustained
ecological monitoring after commercialization.
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12.7 What Are Some Of The Major Ethical
Issues Of Modern Biotechnology?
 What about transgenic animals?
• Some transgenic animals, such as fish, have
the potential to pose significant threats to the
environment.
• If they escaped, they might be more aggressive,
grow faster, or mature faster than wild fish, and
might replace native populations.
• Commercial fish farms market only sterile
transgenic salmon and trout so that escapees
would die without reproducing, and thus have
minimal effect on the environment.
Copyright © 2009 Pearson Education Inc.
12.7 What Are Some Of The Major Ethical
Issues Of Modern Biotechnology?
 Should the genome of humans be changed
by biotechnology?
• Should people be allowed to select, or even
change, the genomes of their offspring?
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parents with genetic disease
fertilized
egg with a
defective
gene
embryo
with a
genetic
defect
baby with
a genetic
disorder
treated culture
therapeutic
gene
viral
vector
Fig. 12-14
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genetically corrected
cell from culture
egg cell
without
a nucleus
genetically
corrected
egg cell
genetically
corrected
clone of the
original embryo
therapeutic
gene
healthy baby
Fig. 12-14
Copyright © 2009 Pearson Education Inc.
12.7 What Are Some Of The Major Ethical
Issues Of Modern Biotechnology?
 If it were possible to insert alleles encoding
functional CFTR proteins into human eggs,
thereby preventing cystic fibrosis, would this
be an ethical change to the human
genome?
 What about making a bigger and stronger
football player?
 When the technology is developed to cure
diseases, it will be difficult to prevent it from
being used for nonmedical purposes.
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