DNA Technology20082009

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Transcript DNA Technology20082009

BIOLOGY
CONCEPTS & CONNECTIONS
Fourth Edition
Neil A. Campbell • Jane B. Reece • Lawrence G. Mitchell • Martha R. Taylor
CHAPTER 12
DNA Technology and
the Human Genome
Modules 12.1 – 12.6
From PowerPoint® Lectures for Biology: Concepts & Connections
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• DNA technology has many useful applications
– The Human Genome Project
– The production of vaccines, cancer drugs, and
pesticides
– Engineered
bacteria that
can clean up
toxic wastes
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Recombinant DNA Technology
• Recombinant DNA technology
– a set of techniques for combining genes from different sources
into a single DNA molecule producing recombinant DNA.
• 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.
• Plasmids are key tools for DNA technology
– Researchers use plasmids to insert genes into bacteria
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1
Bacterium
Plasmid
isolated
2
DNA
isolated
3 Gene
Bacterial
chromosome
Cell containing gene
of interest
inserted
into plasmid
Plasmid
Gene of
interest
Recombinant DNA
(plasmid)
4
DNA
Plasmid put into
bacterial cell
Recombinant
bacterium
5 Cell multiplies with
gene of interest
Copies of gene
Gene for pest
resistance
inserted into
plants
Copies of protein
Clones of cell
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
Figure 12.3
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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.
• Humulin was the first recombinant DNA drug
approved by the FDA.
– DNA technology is also helping medical
researchers develop vaccines.
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12.16 Connection: Recombinant cells and
organisms can mass-produce gene products
• Recombinant cells and organisms are used to
manufacture useful proteins
Table 12.16
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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.
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
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.
– 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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12.18 Connection: Genetically modified organisms
are transforming agriculture
• New genetic varieties of animals and plants are
being produced
– A plant with a new trait can be created using the
Ti plasmid
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Agrobacterium
tumefaciens
DNA containing
gene for desired trait
1
Ti
plasmid
T DNA
Insertion of
gene into plasmid
using restriction
enzyme and DNA
ligase
Plant cell
2
Recombinant
Ti plasmid
Restriction
site
Introduction
into plant
cells in
culture
3
Regeneration
of plant
T DNA
carrying
new gene
within plant
chromosome
Plant with
new trait
Figure 12.18A
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• “Golden rice” has been genetically modified to
contain beta-carotene
– This rice could help prevent vitamin A
deficiency
Figure 12.18B
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Recombinant DNA Techniques
– Recombinant DNA techniques can help
biologists produce large quantities of a desired
protein.
– 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.
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
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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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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2003 Pearson Education
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Figure 12.9
– 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.
– DNA ligase pastes the DNA fragments together
– The result is recombinant DNA
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12.5 Genes can be cloned in recombinant plasmids:
A closer look
• Bacteria take the recombinant plasmids and
reproduce
• This clones the plasmids and the genes they
carry
– Products of the gene can then be harvested
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E. coli
1 Isolate DNA
Human cell
from two sources
2 Cut both
Plasmid
DNAs with
the same
restriction
enzyme
DNA
Gene V
Sticky ends
3 Mix the DNAs; they join
by base-pairing
4 Add DNA ligase
to bond the DNA covalently
Recombinant DNA
plasmid
Gene V
5 Put plasmid into bacterium
by transformation
6 Clone the bacterium
Bacterial clone carrying many
copies of the human gene
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Figure 12.5
DNA Fingerprinting and Forensic Science
– DNA technology has rapidly revolutionized the
field of forensics.
• Forensics is the scientific analysis of evidence from
crime scenes.
– DNA fingerprinting can be used to determine
whether or not two samples of genetic material
are from a particular individual.
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Murder, Paternity, and Ancient DNA
– DNA 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.
– DNA fingerprinting is also used in evolutionary
research
• To study ancient pieces of DNA, such as that of
Cheddar Man.
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 12.12
12.10 Gel electrophoresis sorts DNA molecules by
size
• Restriction fragments of DNA can be sorted by
size
Mixture of DNA
molecules of
different sizes
Longer
molecules
Power
source
Gel
Shorter
molecules
Glass
plates
Completed gel
Figure 12.10
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– The DNA fragments are visualized as “bands” on
the gel.
• The bands of different DNA samples can then be
compared.
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Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 12.17
– One common application of gel electrophoresis
is RFLP analysis
– Restriction fragment analysis is a powerful
method that detects differences in DNA
sequences
• The DNA molecules to be compared are
exposed to a series of restriction enzymes.
• Scientists can compare DNA sequences of
different individuals based on the size of the
fragments
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 12.18
12.14 Connection: The Human Genome Project is
unlocking the secrets of our genes
• The Human Genome Project involves:
– genetic and physical
mapping of chromosomes
– DNA sequencing
– comparison of
human genes
with those of
other species
Figure 12.14
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RISKS AND ETHICAL QUESTIONS
12.20 Connection: Could GM organisms harm
human health or the environment?
• Genetic engineering involves
some risks
– Possible ecological damage
from pollen transfer between
GM and wild crops
– Pollen from a transgenic variety
of corn that contains a pesticide
may stunt or kill monarch
caterpillars
Figure 12.20A, B
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12.21 Connection: DNA technology raises
important ethical questions
• Our new genetic knowledge
will affect our lives in
many ways
• The deciphering of the
human genome, in
particular, raises
profound ethical issues
– Many scientists have
counseled that we
must use the
information wisely
Figure 12.21A-C
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings