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Research - Cloning

June 22, 2017

What is genetics?

The history of genetics began with the work of the Augustinian friar Gregor Mendel.  Mendel’s research on the characteristics of pea plants, which was published in 1866, described how genetic inheritance works.  Through Mendel’s research, we have learned about the tendencies of genes to be inherited, or adopted into one’s genetic makeup.  Inheriting a gene means that it is passed on from one generation to the next.  Although Mendel did not know about DNA at the time of his research, he identified many characteristics of pea plants (height, seed color, and seat coat) and saw that cross-pollinating different types of plants created some interesting combinations.  Mendel’s work paved the way for James Watson and Francis Crick, with the help of Rosalind Franklin, to map the structure of DNA in 1953.  Using x-ray crystallography, they demonstrated that DNA is comprised of two strands, bound together and coiled to form a “double helix” shape.  Watson and Crick received the Nobel Prize in Physiology and Medicine in 1962 for their pioneering work.

 

What is DNA?

DNA, or deoxyribonucleic acid, contains the instructions required for a living organism to develop, survive, and reproduce.  It is the hereditary material in humans and almost all other organisms, which means it is passed on from generation to generation.  Your DNA includes a compendium of the DNA of your ancestors!

DNA is made up entirely of chemical building blocks called nucleotides.  The four types of nucleotides are abbreviated A, C, T, and G, and make up all of our DNA.  DNA contains all of the genetic programming for our cells and has information about our entire makeup – our hair, skin, and eye color, how our brains develop, whether we are lactose intolerant, and more.  The order, or sequence, of these bases determines what our genes are.  For example, the sequence ATCGTT may encode green eyes, while the sequence ATCGCT may encode brown eyes.  

 

What’s in my DNA?

Assuming you had a research laboratory and your DNA samples at the ready, it could take a while to find out what your genes are!  The typical human contains about 3 billion bases and about 20,000 genes on 23 pairs of chromosomes.  The Human Genome Project, which was completed in April 2003, was a group of international, collaborative researchers who mapped the entire human genome over about 15 years.

 

What is cloning?

Cloning refers to the creation of genetically identical copies of a living organism.  The copied material, which has the exact same genetic makeup as the original biological entity, is called a clone.  Cloning doesn’t necessarily mean creating an individual that has the exact same DNA as you – it can refer to any lifeform.  For example, in the scientific laboratory, scientists frequently clone DNA fragments or bacteria for use in experiments.

While cloning has experienced popularity in science fiction, it occurs naturally as well.  Some plants and bacteria clone themselves.  Identical twins are another example of natural clones.  These twins are produced when a fertilized egg splits, creating two or more embryos that carry almost identical DNA.  Identical twins have nearly the same genetic makeup as each other, but they are genetically different from either parent.

In reproductive cloning, researchers remove an adult cell from the animal they wish to duplicate.  They then transfer the DNA of that cell to an egg cell, or oocyte, that has had its own DNA-containing nucleus removed.  The egg is allowed to develop into an early-stage embryo in a test tube, and is then implanted into the womb of an adult female animal for development.  After gestation, the adult female gives birth to an organism that has genetic makeup that is identical to the animal from which they collected the adult cell.[JW2] 

Researchers have cloned cattle, sheep, cat, deer, dog, horse, mule, ox, rabbit, and rat using reproductive cloning.  Cloning an animal can be useful for reviving endangered or extinct species, or cloning cattle and pigs who produce high-quality milk or meat.

 

Can I clone myself?

Cloning humans is highly controversial and raises many ethical, legal, and social questions.  It is currently illegal to clone humans, and nobody has ever successfully accomplished this, but it may be possible in the future.  The process, which remains difficult and inefficient, may be possible in 100 to 1000 years.  However, currently, most embryos fail to develop, or develop abnormally.  The risks and technical challenges of cloning humans make it difficult to clone humans.

 

There are ethical limitations to cloning as well.  It is easy to imagine a world in which the people with the best genes are highly coveted, which would put others, who do not have the favorable genes, at a disadvantage.  For example, cloning geniuses could advance society by creating an intelligent workforce, but this would also make one genetic makeup favorable over others, and cause social problems.  For reasons like these, most scientists and lawmakers currently view human cloning as immoral. 

 

Has anyone ever cloned their pet?

Reproductive cloning enables scientists to produce a copy of an entire animal.  Reproductive cloning was in the limelight in 1998 when Dolly, a sheep, was successfully cloned in 1996.  Dolly was the first mammal ever cloned from an adult cell.   In 2001, CC, aka Copy Cat, became the first cloned cat.  She was born at the Texas A&M University and cloned from a calico cat named Rainbow.  CC is a brown and white cat does not look exactly like Rainbow, who was a domestic shorthair cat with white, brown, and orange coloring.  CC’s owners were not trying to recreate Rainbow, but rather, create a cat with an identical genetic makeup to Rainbow.

 

While it may seem tempting to clone your cat, beware that some aspects of your beloved pet, such as personality, are not entirely explained by one’s DNA.

 

Sources:

Wikipedia

https://www.genome.gov/12011238/an-overview-of-the-human-genome-project/ 

https://ghr.nlm.nih.gov/primer/basics/dna

https://www.genome.gov/25020028/cloning-fact-sheet/ 

 

 

 

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