Download Introduction: Biology Today Chapter 1

Biology Review
DNA is over 99.9 percent
identical for any two people
of the same sex.
http://www.livefromthepit.com
DNA Technology
Note
Much of the text material is from, “Essential Biology with
Physiology” by Neil A. Campbell, Jane B. Reece, and Eric J.
Simon (2004 and 2008). I don’t claim authorship. Other
sources are noted when they are used.
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Outline
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Recombinant DNA
DNA fingerprinting
Genome project
Gene therapy
Safety, ethical, and moral concerns
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Recombinant DNA
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Recombinant DNA
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In the 1940s, researchers demonstrated that the genes from bacteria
could be combined in the laboratory without resorting to normal reproduction.
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Research over a span of 30 years—often using E. coli bacteria—led to
recombinant DNA technology.
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The technology can combine genes from different sources into the DNA
molecule of a host cell.
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Definitions
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A genetically-modified organism (GMO) is one that carries recombinant
DNA.
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A transgenic organism is a GMO that carries DNA from different species.
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http://www.cbs.dtu.dk
Transgenic Organism
This glow-in-the-dark tobacco plant contains genes from
a bioluminescent organism.
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Human Insulin
Insulin is a protein molecule produced by the pancreas to regulate the
level of glucose in the blood.
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Diabetes mellitus results if insufficient insulin is produced.
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A number of unhealthful outcomes can result from untreated diabetes.
http://www.dva.gov.au
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Bovine and Porcine Insulin
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Beginning in the 1920s, diabetes mellitus was treated using insulin
from the pancreases of cows and pigs (bovine and porcine insulin).
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Allergic reactions sometimes resulted because the protein structures
are not exactly the same as in human insulin.
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By the 1970s, the supply of bovine and porcine insulin could not keep
up with demand.
Ala
Thr
Human insulin (to the left) and
porcine insulin—the difference in
the protein structure is just one
amino acid: alanine versus
threonine.
http://www.bio.davidson.edu
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Synthetic Insulin
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Recombinant DNA technology enables the mass production of synthetic
insulin.
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Since the amino acid sequence for human insulin was already known,
researchers could identify the DNA nucleotide sequence that codes for
the protein.
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Individual segments of DNA were synthesized and linked to form human
insulin genes.
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The artificially-produced human genes were inserted into E. coli bacteria
that can rapidly multiply through replication to produce large quantities of
insulin.
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http://www.diabeticmommy.com
Synthetic Insulin (continued)
Today, more than four million people in the United States
rely on synthetic insulin.
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Genetically-Modified Foods
Agricultural crops—including wheat and corn—have been selectively
grown since antiquity to enhance their uses.
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DNA technology is replacing traditional growing programs to improve
productivity.
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Some varieties of corn, for example, have been genetically modified to
resist the European corn borer, an agricultural pest.
http://ipm.uiuc.edu
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What are your thoughts on genetically-modified foods?
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DNA Fingerprinting
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DNA Fingerprinting
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DNA technology has helped to revolutionize forensics, the scientific
analysis of evidence in crime scene and other legal investigations.
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The DNA sequence of every person is unique except in monozygotic
(identical) twins.
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This observation is particularly true of the non-coding, repetitive sections of the nucleotide strands.
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DNA “fingerprinting” can determine to a high degree of certainty if the
genetic material is from the same person or someone else.
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Applications
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DNA fingerprinting has become a standard method for medical forensics, law enforcement, and legal proceedings since its introduction in
1986.
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DNA can be obtained from many body sources including blood, tissues,
hair, bone, saliva, and semen.
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The technique is being used in an increasing number of criminal and civil
cases.
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More Recent Applications
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DNA technology continues to be used in identifying small fragments of
human remains from the terror attacks of September 11, 2001.
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DNA has also been used to exonerate prisoners who were innocent of
the charged crimes.
From the website of an appeals
attorney specializing in DNA evidence.
http://dna.view.com
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DNA Fingerprinting Process
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The analysis of DNA “fingerprints” consists of several major steps:
1. DNA collection, including maintaining the chain of custody.
2. Amplifying (copying) the DNA to provide a sufficient sample for
analysis.
3. Cutting the DNA into fragments and arranging them into a pattern.
4. Comparing the DNA markers or fragments from at least two different sources.
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The amplification process continues to be improved to allow the use of
smaller DNA samples.
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DNA Matching
http://fig.cox.miami.edu
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Establishment of Paternity
In cases involving the establishment of paternity, blood typing can ruleout some possibilities—but it cannot conclusively determine who is the
father of conception.
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Comparing DNA samples from the mother, child, and purported father
can definitively establish paternity.
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Recently, it was shown that Thomas Jefferson (the third U.S. President)
or a close relative fathered at least one of the children of his slave, Sally
Hemings.
http://www.foxnews.com
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http://www.sanger.ac.uk
Human Genome Project
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Human Genome Project
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The human genome has about 3.2 billion nucleotide pairs and 25,000
genes.
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The human genome project by an international consortium of government-funded research groups is completed and much of the data has
been published.
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A complete understanding of the human genome is a challenge due to
its large size and because only small segments of DNA code for mRNA
and tRNA.
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Much of human DNA consists of non-coding, repetitive patterns of nucleotides (A, C, G, and T).
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Repetitive Patterns
Segments of DNA containing thousands of base repetitions occur at the
centromeres and ends of chromosomes (telomeres), possibly for structural support.
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Other repetitive patterns of up to several hundred nucleotides are found
between individual genes.
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The markers used in DNA fingerprinting are the repetitive patterns since
they are unique to the individual.
http://genome.wellcome.ac.ak
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Gene Therapy
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Gene Therapy
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Human gene therapy employs recombinant DNA to treat some types of
disorders and diseases.
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Gene therapy might be used to correct a genetic problem—possibly
permanently, or in other instances, just long enough to treat a medical
problem.
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Gene Therapy Process
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The gene therapy process involves taking a normal gene from a donor,
and isolating and cloning it using recombinant DNA technology.
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The gene of the recombinant DNA is inserted into a vector—usually a
non-harmful DNA virus.
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The virus is injected into the patient so that the gene can insert itself into
the DNA.
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Gene Therapy Process (continued)
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The newly-introduced gene is transcribed and translated to produce
the desired protein.
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Bone marrow stem cells, which produce cells for blood and immune
system, are currently the best candidates for this type of gene therapy.
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http://www.em1.molmed.uni-erlangen.de
Fetal Gene Therapy
The University of Southern California is
a pioneer in fetal gene therapy—the
research is being conducted just a few
miles from the ELAC campus.
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Do you think gene therapy will provide substantial benefits
in the health sciences during your lifetimes?
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Safety, Ethical, and Moral Concerns
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Safety Concerns
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Concerns including that recombinant DNA technology could create
deadly new microbes are being addressed by national governments.
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Laboratories must adhere to strict guidelines to ensure the microbes
are not accidentally released.
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They must adhere to strict procedures
to prevent worker contamination and
infection.
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The microbes are genetically-crippled
so they cannot reproduce and survive
outside the laboratory.
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Potentially dangerous experiments
have been restricted or banned.
Science fiction film from the early-1970s
http://thisdistractedglobe.com
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Ethical and Moral Concerns
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DNA technology raises legal, ethical, and moral questions, and often
with few clear answers.
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Should genetic engineering of gametes and zygotes be permitted for
assuring desirable physical and mental characteristics in children?
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Should we allow genetic changes that could be beneficial today, but
possibly detrimental to the long-term health and survival of a species
including our own?
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Other concerns have been raised too.
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Ethical and Moral Concerns (continued)
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Should we record the DNA fingerprint of every person, possibly as
early as birth?
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Should employers and insurance companies be allowed to screen
job applicants for potentially harmful genes?
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Should we take on a creator role for producing offspring including
humans?
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The list of questions is long—the issues need debate and careful
deliberation by society.
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What do you think about the expanding uses of DNA
technology?
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