Question: How many cellular organisms are needed for cloning?
About the article "Cloning", section "Cloning unicellular organisms".

Candidate passages:
Vegetative reproduction (vegetative propagation, vegetative multiplication, vegetative cloning) is a form of asexual reproduction in plants.
It is a process by which new organisms arise without production of seeds or spores.
It can occur naturally or be induced by horticulturists.
Although most plants normally reproduce sexually, many have the ability for vegetative propagation, or can be vegetatively propagated if small pieces are subjected to chemical (hormonal) treatments.
This is because meristematic cells capable of cellular differentiation are present in many plant tissues.
Horticulturalists are interested in understanding how meristematic cells can be induced to reproduce an entire plant.
Success rates and difficulty of propagation vary greatly.
For example willow and coleus can be propagated merely by inserting a stem in water or moist soil.
On the other hand, monocotyledons, unlike dicotyledons, typically lack a vascular cambium and therefore are harder to propagate. 
Cell cloning.
Cloning unicellular organisms.
Cloning a cell means to derive a population of cells from a single cell.
In the case of unicellular organisms such as bacteria and yeast, this process is remarkably simple and essentially only requires the inoculation of the appropriate medium.
However, in the case of cell cultures from multi-cellular organisms, cell cloning is an arduous task as these cells will not readily grow in standard media.
A useful tissue culture technique used to clone distinct lineages of cell lines involves the use of cloning rings (cylinders).
According to this technique, a single-cell suspension of cells that have been exposed to a mutagenic agent or drug used to drive selection is plated at high dilution to create isolated colonies; each arising from a single and potentially clonal distinct cell.
At an early growth stage when colonies consist of only a few of cells, sterile polystyrene rings (cloning rings), which have been dipped in grease are placed over an individual colony and a small amount of trypsin is added.
Cloned cells are collected from inside the ring and transferred to a new vessel for further growth.
Artificial cloning of organisms may also be called "reproductive cloning". 
A cloning vector is a small piece of DNA, taken from a virus, a plasmid, or the cell of a higher organism, that can be stably maintained in an organism, and into which a foreign DNA fragment can be inserted for cloning purposes.
The vector therefore contains features that allow for the convenient insertion or removal of DNA fragment in or out of the vector, for example by treating the vector and the foreign DNA with a restriction enzyme that creates the same overhang, then ligating the fragments together.
After a DNA fragment has been cloned into a cloning vector, it may be further subcloned into another vector designed for more specific use.
There are many types of cloning vectors, but the most commonly used ones are genetically engineered plasmids.
Cloning is generally first performed using "Escherichia coli", and cloning vectors in "E. coli" include plasmids, bacteriophages (such as phage λ), cosmids, and bacterial artificial chromosomes (BACs).
Some DNA however cannot be stably maintained in "E. coli", for example very large DNA fragment, and other organisms such as yeast may be used.
Cloning vectors in yeast include yeast artificial chromosomes (YACs). 
In bioethics, the ethics of cloning refers to a variety of ethical positions regarding the practice and possibilities of cloning, especially human cloning.
While many of these views are religious in origin, the questions raised by cloning are faced by secular perspectives as well.
Perspectives on human cloning are theoretical, as human therapeutic and reproductive cloning are not commercially used; animals are currently cloned in laboratories and in livestock production.
Advocates support development of therapeutic cloning in order to generate tissues and whole organs to treat patients who otherwise cannot obtain transplants, to avoid the need for immunosuppressive drugs, and to stave off the effects of aging.
Advocates for reproductive cloning believe that parents who cannot otherwise procreate should have access to the technology.
Opponents of cloning have concerns that technology is not yet developed enough to be safe, that it could be prone to abuse (leading to the generation of humans from whom organs and tissues would be harvested), and have concerns about how cloned individuals could integrate with families and with society at large.
Religious groups are divided, with some opposing the technology as usurping God's place and, to the extent embryos are used, destroying a human life; others support therapeutic cloning's potential life-saving benefits.