Reproductive Cloning
the benefits of embryonic cloning
What is reproductive cloning?
• Cloning is the splitting of gametes into daughter cells
consisting of the exact same genes.
• Essentially, a population of almost identical individuals is
created from a single set of genes from a single
organism.
• Favourable traits become common throughout a
population
• Mutation is lessened due to the inactivity of natural
selection
The Short History of Cloning
• The concept of cloning was demonstrated in 1952, using tadpoles
• The first instance of mammalian cloning was successfully carried out
in 1997, resulting in the birth of Dolly, a sheep
Methods of Cloning
• In order to clone, three methods are currently known
• The simplest method is artificial embryo twinning. This method
replicates the natural process in which identical twins are formed
• Somatic Cell Nuclear Transfer (SCNT for short) is a method in which
a genetic replica of a living adult is formed using somatic cells
• These methods have a fairly low success rate; Dolly was the only
embryo to continually grow and mature into a fetus out of 227
experimental embryos
Artificial Embryo Twinning
• Artificial embryo twinning or splitting is a relatively cheap
form of cloning
• It mimics the natural splitting of eggs, which results in
identical twins, triplets, etc.
Blastocyst is held in position
by a micropipette, and
bisected with a surgical
blade
Somatic Cell Nuclear Transfer
Therapeutic Cloning
• In 2001, Advanced Cell Technologies (ACT) in Massachusetts,
announced the first successful cloning of embryos
• The nuclei of embryos collected
from a woman’s uterus were extracted
using a needle no wider than 2/10,000th
of an inch
• A skin cell was inserted via nuclear
transfer to act as the nucleus
• Ionocymin was used to stimulate division.
• Stem cells could be harvested from the egg
after five days of division (blastocyst stage)
Human Cloning
American Association for the Advancement of Science
(AAAS) and numerous groups have acted against
human cloning due to ethical reasons
• Cloning has a very low success rate, and the embryos
that do mature may result in offspring with serious
defects
• Many believe that a cloned human would be
dehumanized
•
Cloning in Food Products
• In 2001, the FDA conducted research
regarding the safety of meat from cloned
livestock
• In 2008, the FDA approved cloning as a
source of meat production
• Due to herds sharing identical genomes,
livestock of better quality is produced
Controversy
• Cloning is seen as unethical by many
• Whether it be humans or frogs,
experimental reproduction is considered
unjust
• Cloning of humans is illegal due to the
apparent immorality in controlling human
birth
Conclusion
• More efficient methods should be
researched, and not practised with larger
mammals
• Embryos should be cloned for further
understanding
Sources
• http://serendip.brynmawr.edu/biology/b103/f00/web1/tamang.html
• http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1476349/
• http://www.ornl.gov/sci/techresources/Human_Genome/elsi/cloning.
shtml
• http://www.ama-assn.org/ama/pub/physician-resources/medicalscience/genetics-molecular-medicine/related-policy-topics/stem-cellresearch/human-cloning.page
• http://www.humancloning.org/benefits.php
• http://es.houstonisd.org/riveroakses/exhibition09/cloning_files/page0
011.htm
• <http://www.fda.gov/AnimalVeterinary/SafetyHealth/AnimalCloning/d
efault.htm>
Picture Sources
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Dolly - http://www.roslin.ed.ac.uk/public-interest/dolly-the-sheep/a-life-ofdolly/
AET - http://www.biolreprod.org/content/66/5/1449.full
SCNT - http://www.biotechnologyonline.gov.au/popups/img_scnt.html
Stem Cells - http://www.scientificamerican.com/article.cfm?id=embryossurvive-stem-cell-harvest