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Biology
A Guide to the Natural World
Chapter 15 • Lecture Outline
The Future Isn’t What It Used to Be: Biotechnology
Fifth Edition
David Krogh
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15.1 What Is Biotechnology?
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What Is Biotechnology?
• Biotechnology can be defined as the use of
technology to control biological processes
as a means of meeting societal needs.
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15.2 Transgenic Biotechnology
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Transgenic Biotechnology
• Human growth hormone is produced within
a bacterium that has been made transgenic
by means of incorporating a human gene.
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Transgenic Biotechnology
• A transgenic organism is an organism
whose genome has stably incorporated one
or more genes from another species.
• Many biotechnology products are produced
within transgenic organisms.
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Restriction Enzymes
• Restriction enzymes are proteins derived
from bacteria that can cut DNA in specific
places.
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Restriction Enzymes
1. A portion of a
DNA strand, highlighted
here, has the recognition
sequence GGATCC.
“sticky ends”
DNA fragment
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2. A restriction enzyme
moves along the DNA
strand until it reaches
the recognition sequence
and makes a cut between
adjacent G nucleotides.
3. A second restriction
enzyme makes another
cut in the strand at the
same recognition
sequence, resulting in a
DNA fragment.
Figure 15.3
Plasmids
• Plasmids are small, extra-chromosomal
rings of bacterial DNA that can exist
outside of bacterial cells and that can move
into these cells through the process of
transformation.
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Plasmids
bacterium
plasmid
bacterial
chromosome
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Figure 15.4
Getting Human Genes into Plasmids
• Human DNA can be inserted into plasmid
rings.
• Scientists use the same restriction enzyme on
both the human DNA of interest and the
plasmids.
• Complementary “sticky ends” of the
fragmented human and plasmid DNA will bond
together, splicing the human DNA into the
plasmid.
• This produces recombinant DNA.
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Recombinant DNA
• Recombinant DNA: two or more segments
of DNA that have been combined by
humans into a sequence that does not exist
in nature.
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Turning out Protein
• Once plasmids have had human DNA
spliced into them, the plasmids can then be
taken up into bacterial cells through
transformation.
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Turning out Protein
• As these cells replicate, producing many
cells, the plasmid DNA inside them
replicates as well.
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Turning out Protein
• These plasmids produce the protein coded
for by the human DNA that has been
spliced into them.
• The result is a quantity of the human protein
of interest.
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human cell containing
gene of interest
bacterium
plasmid
bacterial
DNA
chromosome
protein
synthesis
Use same restriction
enzyme to snip
plasmid.
human protein
of interest
1. Use restriction enzymes
to snip gene of interest
from the isolated human
genome.
recombinant DNA
2. Insert gene into plasmid
(complementary sticky ends
will fit together).
transformation
3. Transfer the plasmid back
into bacterial cell.
4. Let bacterial cells replicate.
Harvest and purify the
human protein produced
by the plasmids inside
the bacterial cells.
replication
bacterial
clones
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Figure 15.5
Plasmids Are One Type of Cloning Vector
• A cloning vector is a self-replicating agent
that functions in the transfer of genetic
material.
• Viruses known as bacteriophages are
another common cloning vector.
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Real-World Transgenic Biology
• A large number of medicines and vaccines
are produced today through transgenic
biotechnology.
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Real-World Transgenic Biology
• Transgenic organisms that are used for this
purpose include not only bacteria but also
yeast, hamster cells, and mammals such as
goats.
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Real-World Transgenic Biology
• Transgenic food crops are planted in
abundance today in the United States.
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Real-World Transgenic Biology
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Figure 15.6
15.3 Reproductive Cloning
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Reproductive Cloning
• A clone is a genetically identical copy of a
biological entity.
• Genes can be cloned, as can cells and
plants.
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Reproductive Cloning
• Reproductive cloning is the process of
making adult clones of mammals of a
defined genotype.
• Dolly the sheep was a reproductive clone.
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Reproductive Cloning
• Today, reproductive cloning of mammals is
carried out through variants of the process
that was used with Dolly.
• This process is called somatic cell nuclear
transfer (SCNT).
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Somatic Cell Nuclear Transfer
(SCNT)
• An egg cell has its nucleus removed and is
fused with an adult cell containing a nucleus
and, therefore, DNA.
• The fused cell then starts to develop as an
embryo and is implanted in a surrogate
mother.
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white
sheep
udder
cells
black-faced
sheep
1. A cell was taken from the udder of a
six-year-old white sheep and then allowed
to divide many times in the laboratory.
Meanwhile an egg was taken from a
black-faced sheep.
egg cell
(nucleus
removed)
DNA
3. The donor cell and egg were put next to
each other, and an electric current was
applied to the egg cell.
4. This caused the two cells to fuse and
prompted an activation that reprogrammed
the donor-cell DNA. This caused the fused
cell to start developing as an embryo.
embryo
surrogate
mother
2. One of the resulting udder cells was
selected to be the “donor” cell for the
cloning. Meanwhile, using a slender tube
called a micropipette, researchers sucked
the DNA out of the egg.
Dolly
5. After some incubation, the embryo was
implanted in a third sheep, which served as
the surrogate mother.
6. This mother gave birth to Dolly the sheep,
which grew into an adult.
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Figure 15.8
Reproductive Cloning
• Reproductive cloning can work in tandem
with various recombinant DNA processes to
produce adult mammals possessing special
traits.
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Reproductive Cloning
• A cell can be made transgenic for such a
trait and then used as the starting cell
(the donor-DNA cell) in producing an
adult mammal with the trait.
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Human Cloning
• A human clone would be a genetic replica
of the person who provided the donor-DNA
cell.
• The donor and his or her clone would be
genetically identical in the same way that
identical twins are.
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15.4 Cell Reprogramming
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Cell Fates: Committed or Not?
• Most cells in the adult human body have
undergone commitment, a developmental
process that results in cells whose roles are
completely determined.
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Cell Fates: Committed or Not?
• Most muscle cells have undergone
commitment, for example, and hence can be
nothing but muscle cells and give rise to
nothing but muscle cells.
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Cell Reprogramming
• Two promising methods exist for generating
human cells that are needed to treat victims
of accident or disease:
• Production through embryonic stem cells
• Production through induced pluripotent stem
cells
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Cell Reprogramming
• Both methods use the reprogramming of
cells to yield desired cell types.
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Embryonic Stem Cells
fertilization
days 1–3
day 5
inner
cell mass
blastocyst
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Figure 15.9
Embryonic Stem Cells
• Cells from the blastocyst’s inner cell mass,
known as embryonic stem cells (ESCs),
can give rise to all the different cell types in
the adult human body.
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Adult Stem Cells
• ESCs stand in contrast to adult stem cells,
which are found, in small numbers, in
various types of tissues in the adult body.
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Adult Stem Cells
• These adult cells have demonstrated some
ability to differentiate into various types of
specialized cells and hence are the subject
of continued research interest.
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Adult Stem Cells
• However, adult stem cells do not have the
differentiation potential of ESCs, nor the
ESC’s ability to continue to produce
specialized cells generation after generation.
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Induced Pluripotent Stem Cells
• In 2007, two research teams developed a
type of human stem cell not derived from an
embryo: the induced pluripotent stem cell
(iPS cell).
• It was first produced by means of splicing
four developmental genes into the genomes
of ordinary adult skin cells.
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Induced Pluripotent Stem Cells
• iPS cells appear to have all the
developmental power of ESC.
• They hold promise of reducing problems of
tissue rejection in medical transplantation
procedures.
• They are being widely used as a means of
studying human disease.
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15.5 Forensic Biotechnology
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Forensic Biotechnology
• Identities of criminals, biological fathers,
and disaster victims often are established
today through the use of forensic DNA
typing.
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Forensic Biotechnology
• Forensic DNA typing is the use of DNA to
establish identities in connection with legal
matters, such as crimes.
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The Use of PCR
• The polymerase chain reaction (PCR) is a
technique for quickly producing many
copies of a segment of DNA.
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1. A researcher selects a
DNA region of interest.
double-stranded
DNA
2. The DNA is heated, causing
the two strands of the double
helix to separate.
single-stranded
DNA
primers
double-stranded
DNA
3. As the mixture cools, short DNA
sequences called primers form
base pairs with complementary
DNA sequences on their
respective strands.
4. DNA polymerase goes down
the line, synthesizing
complementary DNA
strands. The end result is a
doubling of the original DNA.
5. The process is repeated
many times, doubling the
amount of DNA each time.
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Figure 15.11
The Use of PCR
• PCR is useful in situations, such as crime
investigations, in which a large amount of
DNA is needed for analysis, yet the starting
quantity of DNA is small.
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Finding Individual Patterns
• Forensic DNA typing usually works
through comparisons of short tandem repeat
(STR) patterns that are found in all human
genomes.
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Finding Individual Patterns
• Police will compare the STR pattern in a
suspect’s DNA with the STR pattern in
DNA that has been extracted from a crime
scene.
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Copying DNA through PCR
Animation 15.3: Copying DNA through PCR
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15.6 Controversies in Biotechnology
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Controversies in Biotechnology
• Biotech progress also comes slowly because
so many of the processes it is developing
are not just new, but controversial.
• A notable biotech controversy concerns
genetically modified (GM) crops.
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Controversies in Biotechnology
• Opponents of genetically modified crops are
concerned about their effect on human
health and the environment.
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Controversies in Biotechnology
• There is no evidence so far that GM crops
have had detrimental effects in either area.
• But, consumer resistance to the crops has
sharply limited both the types being planted
and the types being put into development.
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Controversies in Biotechnology
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Figure 15.12
Controversies in Biotechnology
• Some biotech controversies are essentially
ethical in nature.
• Among these are the controversies
concerning embryonic stem cells and
therapeutic cloning.
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Controversies in Biotechnology
• A more general controversy has to do with
the question of what level of constraint
society ought to impose on the modification
of living things.
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