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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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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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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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Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings
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
Thursday, May 16th
1. Quick Check
2. Dr. Shephard: Guilty or Innocent?
3. Notes: DNA Fingerprinting and Electrophoresis
(pg 30-31)
Homework: page 6**
** Different from website
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gel electrophoresis
mapping your genome23 and me website
Dr. Shephard
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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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• 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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Figure 12.15
Gel Electrophoresis
• Gel Electrophoresis
– Can be used to separate the DNA fragments
obtained from different sources.
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Friday, April 17th
1. Review DNA Fingerprinting and
Electrophoresis and page 6
2. Electrophoresis practice: page 12-13
3. DNA GOES to the Races: page 8-9
** above is homework if not completed in class***
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings
gel electrophoresis
mapping your genome23 and me website
Dr. Shephard
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Figure 12.12
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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