Download Ethical Issues in Genetics

Ethical Issues in Genetics
Step One:
Please use the following short articles, video clips and animations to educate yourself as to how we have
moved from traditional means of manupulating genes such as selective breeding to the modern
techniques of genetic engineering and cloning.
Selective Breeding
Cattle originally evolved over millions of years through a process of natural selection-also known as
“survival of the fittest”-which made them adaptable to a wide variety of environments, including most of
those inhabited by another highly adaptable species: humans. Once humans discovered how to
domesticate cattle about 4,000 years ago, they began to selectively, or “artificially,” breed them for
specific desired traits like meat and milk production. This resulted in animals fit less for survival in the
wild than the satisfaction of human needs, but in purely genetic terms, the arrangement has proven
highly successful for cattle. Cattle now thrive throughout the world in over 800 different breeds, each
more or less successfully adapted to their environment and the needs of their human caretakers.
Cattle Genetic Engineering Video:
http://www.teachersdomain.org/resource/nat08.living.gen.geneng.traits/
*How many different breeds of cattle have humans created?
*This video does not show genetic engineering, rather it explains selective breeding. Explain what is
meant by selective breeding.
* Besides milk and meat production, what other traits might humans with to breed in cattle?
Genetic Engineering in Plants
It seems like such an elegant use of genetic engineering.
Splice the genes for a naturally pest-killing microbe into a crop plant so that the corn or wheat or potato
plants themselves become lethal to the pests. No more wasteful -- and expensive -- spraying of toxic
pesticides. Instead, the bugs taste the leaves and go off to die.
Indisputably, it works. The genes of Bacillus thuringiensis, or Bt, have been added to corn, cotton,
potatoes, and other crops, with the desired results. Scientists are aware, however, that any effort to
manipulate the ecological balance must reckon with the evolutionary consequences. So even before the
first Bt crops were planted, scientists, farmers, and regulators began worrying about unintended effects.
For example, insects that feed on the Bt-enhanced plants are continuously exposed to the lethal Bt toxin,
not intermittently exposed, as when Bt is sprayed. The plants kill most of the insects, but a few bugs will
survive because of random mutations that make them resistant.
They'll not only survive, but they'll gain a reproductive edge, breeding with each other to create strains of
Bt-resistant bugs that could dominate an area. The greatest fear is that the resistant insects would
prevail to such an extent that Bt in the form of a spray, used by organic farmers for more than 50 years,
might become useless too.
To forestall this catastrophe, the federal Environmental Protection Agency called for farmers to create
"refuges" -- fields planted with the original, non-Bt-modified crops. In these refuges the pests'
reproduction will be free of the selection pressures favoring resistant mutants. The few Bt-immune
individuals will be overwhelmed by the wild-type, Bt-susceptible insects. And when the resistant bugs
mate with the wild-type individuals, their offspring will be vulnerable to the Bt toxin.
There's general agreement refuges should work. The questions arise over how large the refuges must be
(as a percentage of the farmer's total crop planting) and whether the requirement will be economically
disadvantageous to farmers.
For example, they would have to spray the refuge crops with traditional Bt pesticide -- so why not just
spray all the crops with it? The debate goes on, and the problem remains unresolved.
Genetic Engineering Videos:
http://www.teachersdomain.org/resource/tdc02.sci.life.gen.btcorn/
http://www.teachersdomain.org/asset/tdc02_vid_breeding/
 How is Bt introduced into the genes of corn? What is this process called?
 How is Bt used differently for organic farming than in biotech corn?
 How is genetic engineering different than selective breeding?
Cloning
Reproductive cloning is a technology used to produce a genetically identical copy of another living thing.
Two techniques used to do this are artificial embryo "twinning" and somatic cell nuclear transfer (SCNT).
Artificial embryo twinning mimics the natural way twins develop. Scientists separate an early-stage
embryo into two or more individual cells, and each cell is left to divide and develop into an embryo. The
embryos are implanted in the uterus of a female surrogate and carried to term. Because the twinned
embryos come from the same zygote, they are genetically identical.
In SCNT, scientists transfer genetic material from the nucleus of a somatic cell to an egg cell whose
nucleus has been removed. (A somatic cell is any body cell, except for a male or female sex cell.) To
stimulate cell division, either electrical current or special chemicals are applied to the modified egg. As
with twinning, the cloned embryo is eventually implanted into the uterus of a surrogate female and
carried to term.
Dolly, or any other animal cloned using SCNT, is not an exact replica of the donor animal. Because some
of the clone's genetic materials come from the host egg cell's mitochondria, only the clone's nuclear DNA
matches the donor's. Also, because the environment influences physical traits and personality, a clone's
appearance and character will inevitably differ from the donor's. In addition, cloned animals like Dolly
have shown signs of premature aging.
Hundreds of animal clones developed through SCNT have been born since Dolly, including other sheep,
goats, cows, mice, pigs, cats, and rabbits. But the success rate for reproductive cloning is low. In fact,
attempts at cloning other species—such as monkeys, chickens, and horses—have been entirely
unsuccessful to date. Many of the animals that have been born suffer from health complications and die
prematurely. Still, reproductive cloning has provided scientists with some important lessons. For
example, they've learned that specialized cells are not permanently fixed, as previously believed. Dolly
was produced from a single adult udder cell that was reprogrammed to generate an entire new organism.
Cloning Interactive Animation:
http://www.teachersdomain.org/resource/biot09.sci.life.gen.cloning/

During embryonic development all cells derived from the zygote contain the same DNA
but yet differentiate into cells with different structures and functions to make the organs
(e.g., muscle, blood, nerve cells). Explain how this occurs.

What did scientists learn about cell differentiation with the birth of Dolly the sheep?

What type of cell was used to fuse with a donor egg cell to produce Dolly?

How many different sheep were involved in creating Dolly? Describe the role of each.

Distinguish between the procedures used to create the cloned sheep and the cloned
mice.
Step Two: Formulate an opinion.
Do the benefits of genetic engineering outweigh the risks? In your answer please cite specific examples
of the benefits and risks of genetic engineering. Finally, give your opinion.
Step Three: Take a stand.
See how your opinions on genetic engineering compare to those of your classmates.
Lessons found @ http://www.teachersdomain.org/browse/?fq_hierarchy=k12.sci.life.gen.engineering