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CHAPTER 12
DNA Technology
PowerPoint® Lectures for
Essential Biology, Third Edition
– Neil Campbell, Jane Reece, and Eric Simon
Essential Biology with Physiology, Second Edition
– Neil Campbell, Jane Reece, and Eric Simon
Lectures by Chris C. Romero
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Biology and Society: Crime Scene
Investigations: Murders in a Small Town
• On November 22, 1983,
– A 15-year-old girl was raped and murdered on a
quiet country lane.
– Three years later, another 15-year-old girl was
raped and murdered.
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• DNA fingerprinting of DNA samples from suspects
and the crime scene
– Proved one man guilty and another man innocent.
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Figure 12.1
Recombinant DNA Technology
• Recombinant DNA technology is a set of
techniques for combining genes from different
sources into a single DNA molecule.
– An organism that carries recombinant DNA is
called a genetically modified (GM) organism.
• Recombinant DNA technology is applied in the
field of biotechnology.
– Biotechnology uses various organisms to perform
practical tasks.
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Figure 12.2
From Humulin to Genetically Modified Foods
• By transferring the gene for a desired protein
product into a bacterium, proteins can be produced
in large quantities.
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Making Humulin
• In 1982, the world’s first genetically engineered
pharmaceutical product was produced.
– Humulin, human insulin, was produced by
genetically modified bacteria.
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Unnumbered Figure p. 222
• Humulin was the first recombinant DNA drug
approved by the FDA.
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Figure 12.3
• DNA technology is also helping medical
researchers develop vaccines.
– A vaccine is a harmless variant or derivative of a
pathogen.
– Vaccines are used to prevent infectious diseases.
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Genetically Modified (GM) Foods
• Today, DNA technology is quickly replacing
traditional plant-breeding programs.
– In the United States today, roughly one-half of the
corn crop and over three-quarters of the soybean
and cotton crops are genetically modified.
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• Corn has been genetically modified to resist insect
infestation.
– This corn has been damaged by the European
corn borer.
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Figure 12.4
• “Golden rice” has been genetically modified to
contain beta-carotene.
– Our bodies use beta-carotene to make vitamin A.
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Figure 12.5
Farm Animals and “Pharm” Animals
• While transgenic plants are used today as
commercial products, transgenic whole animals are
currently only in the testing phase.
• These transgenic sheep carry a gene for a human
blood protein.
– This protein may help in the treatment of cystic
fibrosis.
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Figure 12.6
• While transgenic animals are currently used to
produce potentially useful proteins, none are yet
found in our food supply.
• It is possible that DNA technology will eventually
replace traditional animal breeding.
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Recombinant DNA Techniques
• Bacteria are the workhorses of modern
biotechnology.
• To work with genes in the laboratory, biologists
often use bacterial plasmids.
– Plasmids are small, circular DNA molecules that
are separate from the much larger bacterial
chromosome.
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Figure 12.7
• Plasmids can easily incorporate foreign DNA.
• Plasmids are readily taken up by bacterial cells.
– Plasmids then act as vectors, DNA carriers that
move genes from one cell to another.
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• Recombinant DNA techniques can help biologists
produce large quantities of a desired protein.
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Glow in the Dark Fish
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Review
1. What is Recombinant DNA technology?
2. What is needed (ingredients)?
3. What are applications of this process?
What you need to Know about DNA Technology.
1. Technique
2. Purpose
3. Pros/Cons
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Figure 12.8
A Closer Look: Cutting and Pasting DNA with
Restriction Enzymes
• Recombinant DNA is produced by combining two
ingredients:
– A bacterial plasmid
– The gene of interest
• To combine these ingredients, a piece of DNA
must be spliced into a plasmid.
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• This splicing process can be accomplished using
restriction enzymes.
– These enzymes cut DNA at specific nucleotide
sequences.
• These cuts produce pieces of DNA called
restriction fragments
– That may have “sticky ends” that are important
for joining DNA from different sources.
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Figure 12.9
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Read background information and underline answers to:
-What is recombinant DNA?
-What is a plasmid?
-What occurs at the origin of replication?
-What are ampicillin and kanamycin?
-What are pAMP and pKAN?
-What role do bacteria play?
http://www.sumanasinc.com/webcontent/animations
/content/plasmidcloning.html
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Bacterial growth without plasmid:
No antibiotics
Ampicillin
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Kanamycin
Ampicillin&
Kanamycin
Bacterial growth without plasmid:
No antibiotics
Ampicillin
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Kanamycin
Ampicillin&
Kanamycin
Bacterial growth with plasmid:
No antibiotics
Ampicillin
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Kanamycin
Ampicillin&
Kanamycin
Bacterial growth with plasmid:
No antibiotics
Ampicillin
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Kanamycin
Ampicillin&
Kanamycin
Recombinant Paper Plasmid lab
1. pAMP =
pKAN =
1A (amp) and
1B
2 A (kan)
2B
and
1A + 1B (resistant to amp)
1B + 2B (no resistance)
1A + 2B (resistant to amp)
2A + 1B (no origin of rep)
1A + 2A (resistant to both)
2A + 2B (resistant to kan)
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Recombinant paper plasmid lab
2.
No antibiotics
+ plasmid
No antibiotics
- plasmid
Amp
+ plasmid
Amp
- plasmid
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Kan
+ plasmid
Kan
- plasmid
Amp/Kan
+ plasmid
Amp/Kan
- plasmid
Recombinant Paper Plasmid lab
3. pAMP =
pKAN =
1A (amp) and
1B
2 A (kan)
2B
and
Would survive on one antibiotic but not the other!
1A + 1B (resistant to amp)
1A + 2B (resistant to amp)
2A + 2B (resistant to kan)
2A + 1B (resistant to kan, but no origin of rep)
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Recombinant Paper Plasmid Lab
4. The most important reason is so that scientists
can identify bacteria that have been
transformed.
- Can select only bacteria that have the gene of
interest!
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A Closer Look: Obtaining the Gene of Interest
• How can a researcher obtain DNA that encodes a
particular gene of interest?
• The “shotgun” approach is one way to synthesize a
gene of interest.
– Millions of recombinant plasmids containing
different segments of foreign DNA are produced.
– This collection is called a genomic library.
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• Once a genomic library is created, biologists must
identify the bacterial clone containing the desired
gene.
– A specific sequence of radioactive nucleotides
matching those in the desired gene can be created.
– This type of labeled nucleic acid molecule is
called a nucleic acid probe.
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Figure 12.10
• Reverse transcriptase is another method for
synthesizing a gene of interest.
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Figure 12.11
DNA Profiling and Forensic Science
• DNA technology has rapidly revolutionized the
field of forensics.
– Forensics is the scientific analysis of evidence
from crime scenes.
• DNA profiling can be used to determine whether or
not two samples of genetic material are from a
particular individual.
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Figure 12.12
Murder, Paternity, and Ancient DNA
• DNA profiling (fingerprinting)
– Has become a standard criminology tool.
– Has been used to identify victims of the
September 11, 2001, World Trade Center attack.
– Can be used in paternity cases.
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• DNA fingerprinting is also used in evolutionary
research
– To study ancient pieces of DNA, such as that of
Cheddar Man.
– Found in a cave near Cheddar, England
– Direct ancestor of local teacher
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Figure 12.13
DNA Fingerprinting Techniques
The Polymerase Chain Reaction (PCR)
• The polymerase chain reaction (PCR) is a
technique by which any segment of DNA can be
copied quickly and precisely.
– Through PCR, scientists can obtain enough DNA
from even minute amounts of blood or other
tissue to allow DNA profiling.
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Figure 12.14
Short Tandem Repeat (STR) Analysis
• How do you prove that two samples of DNA come
from the same person?
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• Short tandem repeats (STRs)
– Are repetitive sequences of DNA that are repeated
various times in the genome.
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• Scientists use STR analysis
– To compare the number of repeats between
different samples of DNA.
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Figure 12.15
• Once a set of DNA fragments is prepared,
– The next step in STR analysis is to determine the
lengths of these fragments.
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Gel Electrophoresis
• Gel Electrophoresis
– Can be used to separate the DNA fragments
obtained from different sources.
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Figure 12.16
• The DNA fragments are visualized as “bands” on
the gel.
– The bands of different DNA samples can then be
compared.
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Figure 12.17
• One common application of gel electrophoresis is
RFLP analysis,
– In which DNA molecules to be compared are
exposed to a series of restriction enzymes.
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Figure 12.18
Genomics and Proteomics
• Genomics is the science of studying whole
genomes.
– The first targets of genomics were bacteria.
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Table 12.1
The Human Genome Project
• In 1990, an international consortium of
government-funded researchers began the Human
Genome Project.
– The goal of the project was to sequence the
human genome.
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• Sequencing of the human genome presented a
major challenge.
– It is very large.
– Only a small amount of our total DNA is
contained in genes that code for proteins.
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• The Human Genome Project
– Can help map specific disease genes such as
Parkinson’s disease.
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Figure 12.20
Genome-Mapping Techniques
• The Human Genome Project proceeded through
several stages,
– During which preliminary maps were created and
refined.
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• The whole-genome shotgun method
– Involves sequencing DNA fragments from an
entire genome and reassembling them in a single
stage.
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Figure 12.21
The Process of Science:
Can Genomics Cure Cancer?
• In 2003, the Food and Drug Administration
– Approved the drug gefinitib for the treatment of
lung cancer.
• Unfortunately, gefinitib is ineffective for many
patients.
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• A 2004 study found that genetic differences among
patients affected their response to the drug,
– Exhibiting how genomics can affect the treatment
of disease.
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Figure 12.22
Proteomics
• Success in genomics has given rise to proteomics,
– The systematic study of the full set of proteins
found in organisms.
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Human Gene Therapy
• Human gene therapy is a recombinant DNA
procedure that seeks to treat disease by altering the
genes of the afflicted person.
– The mutant version of a gene is replaced or
supplemented with a properly functioning one.
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Figure 12.23
Treating Severe Combined Immunodeficiency
• SCID is a fatal inherited disease caused by a single
defective gene.
– The gene prevents the development of the
immune system.
– SCID patients quickly die unless treated with a
bone marrow transplant.
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• Since the year 2000,
– Gene therapy has successfully cured 22 children
with inborn SCID.
• Unfortunately, three of the children developed
leukemia and one of them died.
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Safety and Ethical Issues
• As soon as scientists realized the power of DNA
technology, they began to worry about potential
dangers such as:
– The creation of hazardous new pathogens
– The transfer of cancer genes into infectious
bacteria and viruses
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• Strict laboratory safety procedures have been
designed to protect researchers from infection by
engineered microbes.
– Procedures have also been designed to prevent
microbes from accidentally leaving the
laboratory.
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Figure 12.24
The Controversy over Genetically Modified Foods
• GM strains account for a significant percentage of
several agricultural crops in the United States.
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Figure 12.25
• Advocates of a cautious approach have some
concerns:
– Crops carrying genes from other species might
harm the environment.
– GM foods could be hazardous to human health.
– Transgenic plants might pass their genes to close
relatives in nearby wild areas.
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• Negotiators from 130 countries (including the
United States) agreed on a Biosafety Protocol.
– The protocol requires exporters to identify GM
organisms present in bulk food shipments.
• Several U.S. regulatory agencies evaluate
biotechnology projects for potential risks:
– Department of Agriculture
– Food and Drug Administration
– Environmental Protection Agency
– National Institutes of Health
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Ethical Questions Raised by DNA Technology
• Should genetically engineered human growth
hormone be used to stimulate growth in HGHdeficient children?
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Figure 12.26
• Genetic engineering of gametes and zygotes has
been accomplished in lab animals.
– Should we try to eliminate genetic defects in our
children?
– Should we interfere with evolution in this way?
• Advances in genetic fingerprinting raise privacy
issues.
• What about the information obtained in the Human
Genome Project?
– How do we prevent genetic information from
being used in a discriminatory manner?
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Evolution Connection:
Genomes Hold Clues to Evolution
• Genome data has confirmed evolutionary
connections.
• Comparisons of completed genome sequences
strongly support the theory that there are three
fundamental domains of life:
– Bacteria
– Archaea
– Eukaryotes
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