Unit 2: Genetic Processes
Lesson 3: Cloning and Biotechnology
In nature, many organisms reproduce asexually by mitotic cell division. The offspring, which are
genetically identical to the parent, are referred to as clones.
Cloning: the process of producing one individual that is genetically identical to another, using a
single cell or tissue.
Cloning occurs naturally for many organisms, and through the use of biotechnology, a field of biology
that involves the use of living things in engineering, industry and medicine, cloning can be done for
organisms that do not normally produce clones.
Plant Cloning:
Humans have been using simple methods of plant cloning, such as cuttings and grafting, for over 2000
years. In 1958, plant biologist Fredrick Steward announced his success in cloning a plant in a laboratory
from a single carrot cell. Steward was able to clone a carrot plant beginning with mature, specialized
cells from another carrot. By growing individual root cells in a nutrient rich medium containing some plant
hormones, Steward was able to get the cells to return to an undifferentiated state (lacking any
resemblance to carrot tissues). The cells then restarted the process of growth, specialization and
development into new plants.
What are some uses for plant cloning?
What might be some disadvantages associated with plant cloning?
Animal Cloning:
The first animal cloning experiment was done on frogs, whereby a fertilized nucleus was used as
the source of DNA. In this experiment, the nucleus from a frog embryo was removed and inserted into
an enucleated cell. This resulted in a clone of the donor embryo. This experiment was done in the 1950s.
On July 5, 1996, the world’s most famous sheep, Dolly was born. What was remarkable about this
cloning was that it was the first mammal cloned from an adult body cell. The difficulty with adult body
cells compared to an embryonic cell, is that adult body cells have undergone too much cell
differentiation. This makes it difficult to stimulate the growth and differentiation process necessary to
develop a fertilized egg. Dr. Ian Wilmut of the Roslin Institute of Scotland, got around this situation by
fusing the adult body cell with an enucleated egg cell and triggering it to start dividing and growing into
an embryo. This embryo was then implanted into a surrogate sheep and five months later, Dolly was born.
Six years later, Dolly died of lung disease and displayed signs of premature aging including arthritis.
Typically, clones do not live as long as normal individuals and often suffer from a variety of health
complications.
What would be some advantages to animal cloning?
What might be some ethical concerns about animal cloning?
Genetically Modified Organisms (GMOs)
Genetically modified organisms often carry genes that originated in a different species.
Homework:
1. Why might it be advantageous to clone a prize animal rather than simply breeding it with other
individuals? What might be the disadvantages?
2. How does the use of cloned prize plants and animals reduce the possibility of improving these
same species?
3. A couple paid more than $150000 to have their deceased pet dog Lancelot cloned. They already
had eight other dogs at the time. How does this news story make you feel? Do you think its
acceptable to spend that much money on cloning a pet? How does it compare to spending a similar
amount of money on an exotic sports car?
4. There are many applications of cloning technology. List the applications that you think are most
acceptable and those that are least acceptable. Explain your reasoning.
5. There is little doubt that it will soon be technologically possible to clone humans. Commen on the
concept of cloning humans. What argument do you think people will make in support of, and in
opposition to, human cloning?
Solutions: