chapt 11

gooseliverBiotechnology

Oct 22, 2013 (3 years and 11 months ago)

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Chapter 11


Lecture Outline


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Why Biotechnology Works


Biotechnology is a collection of laboratory
techniques that involve the direct
manipulation of an organism’s DNA.


Biotechnology has allowed for:


Cheaper and more effective drugs


The correction of genetic mutation


The creation of cells that can clean
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up
environmental messes


An increase in agricultural productivity

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Understanding Biotechnology


Biotechnology is based on our understanding of the
structure of DNA.


In the nucleus, chromosomes are made of


DNA


Histone proteins


DNA is the genetic material of the cell.


The information is in the sequence of nucleotides in the
DNA.


Genes are regions of DNA that encode for specific proteins.


Proteins produce the characteristics of cells (phenotype).


Biotechnology involves the manipulation of DNA in
order to change phenotype.

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Comparing DNA


Organisms that have similar phenotypes
have similar DNA sequences.


DNA between two organisms can be
compared in a couple of different ways:


DNA fingerprinting


DNA sequencing

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DNA Fingerprinting


Uniquely identifies individuals on the basis of DNA
fragment lengths.


Fragments are generated by restriction enzymes that
cut DNA at specific sites.


Each individual’s DNA is different enough that these
enzymes will generate different lengths of fragments in
two different individuals.


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Variable Number Tandem
Repeats (VNTR)


Variable number tandem
repeats are regions of
DNA that are repetitive
sequences.


Each person has a
slightly different number
of repeats.


Therefore, if these
regions are cut with
restriction enzymes, each
person will have a
different set of fragments.

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Other Techniques Used in DNA
Fingerprinting


Polymerase chain reaction


DNA replication in a test tube


Uses primers that dictate the region of DNA to be
copied


Makes many copies of a particular segment of
DNA


This creates enough material for scientists to
perform DNA fingerprinting.

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Polymerase Chain Reaction

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Other Techniques Used in DNA
Fingerprinting


Electrophoresis


A way to separate DNA fragments based on their
length


DNA sample is loaded into a gel matrix and an
electrical current is applied.


Smaller fragments travel through the gel faster.


Creates a banding pattern of fragments


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Electrophoresis

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DNA Fingerprinting Technique


DNA is obtained from two sources:


Blood at a crime scene


Hair from the crime suspect


Polymerase chain reaction is used to make many
copies of a VNTR region.


Restriction enzymes are used to cut the VNTRs into
fragments.


The fragments are separated by electrophoresis.


The patterns of the two DNA samples are compared.


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DNA Fingerprinting Applications


DNA fingerprinting can identify if two samples
of DNA came from the same person.


Used in the prosecution of crime suspects


Used in paternity cases

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DNA Fingerprinting

in a Crime Case

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DNA Fingerprinting

in a Paternity Case

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DNA Sequencing


A specially engineered DNA replication reaction.


The DNA of interest is the template.


Uses DNA polymerase


Uses a primer (gives DNA polymerase a place to start)


Uses regular nucleotides (A,T,G,C)


Uses special fluorescently
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labeled dideoxynucleotides


When these are added to the growing chain, replication will
stop.


The fragment will be fluorescently labeled as well.


Fragments are separated by electrophoresis, and the
sequence can be read.

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DNA Sequencing

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The Human Genome Project


A massive collaborative effort to determine
the sequence of DNA in all human
chromosomes.


Started with physical maps of chromosomes


Determines the location of specific markers on the
chromosomes


DNA sequencing determined the exact
nucleotide sequence between each marker.

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Genes Known to be on Human
Chromosome 21

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Human Genome Project
Applications


Disease diagnosis


Discovery of new family of proteins


Better understanding of basic biology


The human genome project found that there are far
fewer genes in the human genome than previously
predicted.


Each gene can be alternatively spliced to code for several
proteins.

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Different Proteins


One Gene

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Other Genomes


The genomes of other organisms have also been
sequenced.

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Patterns in Protein Coding


The human genome was compared to these
other genomes.


Several types of patterns were found.


Tandem clusters
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grouped copies of the same gene


Segmental duplications
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groups of genes copied from
one chromosome and moved to another chromosome


Multigene families are groups of different genes that are
closely related.


The parts of these proteins that are similar represent
important regions of the proteins that are crucial to their
function.


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Patterns in Protein Coding
Sequences

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New Fields of Knowledge


Recent developments in genome sequencing
have led to three new fields in biology.


Genomics


The comparison of genomes from different species


Identifies species relatedness and gene similarities


Transcriptomics


Examines when, where and how much mRNA for a
given gene is made


Proteomics


Examines the proteins that are predicted from the DNA
sequence


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Genetic Modification

of Organisms


It is now possible to clone genes and move them from
one organism to another.


Called gene cloning


DNA sequences can be altered (mutated) to generate a
desired change.


The new DNA is called recombinant DNA.


Once the DNA is transferred, the new host cell begins to
make the new DNA and produce the new proteins.


Organisms that contain recombinant DNA are called
“genetically modified organisms”.


Usually involves bacteria or viruses that will make
large amounts of the protein of interest


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How to Clone a Gene


Cut the gene of interest out of the
chromosome using restriction enzymes.

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How to Clone a Gene


Splice the fragment
containing the gene into
a carrier molecule,
usually a bacterial
plasmid.

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How to Clone a Gene


Insert the plasmid with the fragment into the bacterial
cells.



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How to Clone a Gene


Each time the bacterial cells divide, many copies of
the gene will be made.


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Human Insulin from Bacteria

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Genetically Modified Organisms


Genetically modified organisms have been
used to:


Make human insulin


Generate “Golden rice”


Make interferon


Make human growth hormone

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Genetically Modified Organisms


For bioremediation (the use of living organisms to
remove toxins from the environment)


Generate crops that supply developing nations
with nutrients not normally found in their native
plants


Generate crops that can manufacture medicines
to treat disease


Generate crops that are resistant to herbicides or
that make their own insecticides


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Gene Therapy


Recombinant DNA technology can be used
to administer gene therapy.


Gene therapy involves manipulating genes in
order to cure or treat a genetic disease.

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Gene Therapy


Gene therapies must be specifically
designed for each situation.


If the mutant gene is not functional, then a
functional gene must be inserted.


If the mutant gene is overactive, then it must be
deleted or altered.


Usually involves mutating the part of the gene that
controls its activation


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The Process of Gene Therapy

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Cloning Organisms


Recombinant DNA technologies have also enabled
scientists to clone entire organisms.


Cloning in the laboratory involves a process called
somatic cell nuclear transfer.


First, a nucleus must be removed from a cell of the
organism that is to be cloned.


The nucleus is then placed into an enucleated egg.


The egg is stimulated to divide and is artificially implanted
into a host mother.


Several species have been successfully cloned.


Sheep, cats, monkeys, etc.

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Cloning Dolly, the Sheep

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The Scientific Relevance

of Cloning


Cloning has advanced our understanding of
developmental processes.


Determination is the process a cell goes through
to select which genes it will express.


Differentiation is the process of expressing those
genes and becoming a specific cell type.


The cloning of Dolly illustrated that
determination can be reversed and a fully
differentiated cell can be used to clone an
organism.

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Stem Cells


Stem cells have not completed the
determination and differentiation process, so
they have the potential to develop into many
different cell types.


Stem cells could be used to replace damaged
tissues and organs in humans.


Could be used to cure diseases


Parkinson’s disease


Diabetes

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Embryonic Stem Cells


Embryonic stem cells come from embryos
and have not completed the process of
determination.


These have great potential.


However, embryos must be destroyed in order to
obtain them and work with them.

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The Culturing of Embryonic

Stem Cells

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Adult Stem Cells


Adult stem cells have partially completed the
process of determination.


These have less potential; they are already
specific tissue types (blood, bone, etc).


There is no ethical dilemma in obtaining them.

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The Differentiation of Blood
Cells

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Personalized Stem Cell Lines


Combining somatic cell nuclear transfer and
stem cells may allow scientists to create
personalized stem cell lines.


The individual’s nucleus would be transferred to
an egg.


The egg would be allowed to divide to the point
where it produced embryonic stem cells.


Could potentially be used to grow tissues or
organs (in the future; not possible now).

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Personalized Stem Cell Lines

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Biotechnology Ethics


The recent advances in biotechnology
have raised a number of ethical
questions.


Will the technology be used safely?


Who will benefit?


Who will suffer?


Should the technology be used to make a
profit?


Just because we can, should we?

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What are the consequences?


One approach to ethics is to weigh the “pros”
and “cons” of the particular technology or
application.


Genetic testing allows us to predict disease
before it happens.


Pro: This allows one to seek treatment early.


Con: If insurance companies obtain this information,
they may deny coverage.

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What are the consequences?


Cloning technology allows us to generate
nutritionally advanced foods.


Pro: This provides underdeveloped nations with better
food sources.


Con: The GMO organisms may impact the ecosystem
negatively.


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Is it inherently wrong?


Another approach to ethics is to ask if the
technology and its application violates
principles that are valued by society.


Does it threaten someone’s human rights?


Does it threaten someone’s Bill of Rights?


Does it violate someone’s religious beliefs?


Does it diminish someone’s quality of life?


Does it violate animal rights?

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Is it inherently wrong?


Is it inherently wrong to…


Produce genetically modified organisms?


Manipulate genes?


Manipulate or destroy embryos to obtain stem
cells?