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CLONING
Cloning as a reproductive technology arouses more
controversy than other reproductive technologies. Images
of drone armies or Nazi inspired super-races quickly arise,
along with more subtle and far-reaching fears such as
humanness valued only within the limited scope of what is
understood as desirable within specific cultural contexts.
Cloning is a term popularly used to describe any
procedure asexually producing a genetic replica of a
biological object. This might be replication of a DNA
sequence, a cell or a whole organism, either plant or
animal. Identical twins may be said to be clones, as they are formed through cell
splitting or mitotic reproduction. To take a cutting from a plant and grow the
cutting, is cloning. Scientists have been cloning frogs from around 1970. It is the
actual cloning of mammals, the cloning of human tissue and cells and with this,
the potential cloning of human beings, which is deeply provocative. Some of the
discussion surrounding the alleged human cloning by the Raelian sect may be
relevant, but is not addressed here as the claim is yet to be substantiated.
Cloning might be performed for two reasons:

To produce beings genetically identical to the cell donor. This is known as
human reproductive cloning.

To produce human cell tissue for research or manufacture theraputic
products including tissues for transplantation. This is known as human
theraputic cloning.
or
In order to perform different tasks within the body, cells are differentiated. From
fertilisation until around the 16 cell stage, cells are totipotent, or totally potent.
This means they are undifferentiated and are capable of forming into any type of
body cell. Theoretically, each totipotent cell might replicate to become a new
human being. These totipotent cells are also known as blastomeres and stem
cells.
From the 16 cell stage and onwards, cells differentiate. At this stage and until
implantation of the blastocyst or very early embryo, into the uterus at around 6
days, differentiation is limited to cells that will become the placenta and cells that
will become the foetus. After implantation and with the continuing growth of the
blastocyst into the embryo, cells differentiate into the three major tissue types:
endoderm or interior gut lining, mesoderm or muscle, bone, blood, and ectoderm
or epidermal tissues and nervous system. Cells continue to differentiate further
into all body cells. These early differentiated cells are called pluripotent or
multipotent cells and are still known as stem cells.
Blastocyst at 5 days
Research on stem cells is permitted in
Australia up until the 14 day stage.
This means until around 8 days after
implantation in the uterus would have
taken place. Depending on the level of
cell differentiation, stem cells may
eventually become any specialised
body tissue. However, also depending
on the degree of differentiation, they
may not become a whole new human
being. For example, stem cells that
have differentiated into placenta cells
may not develop into a whole new
human being, but stem cells that have
differentiated into foetal cells may
theoretically develop into a whole new
human being. Much stem cell research is focused around understanding and
manipulating the transformation of totipotent cells into pluripotent cells and vice
versa, along with understanding and manipulating the processes of cell
differentiation.
Thus the very early fertilized ova might be used for human reproductive cloning
and for human theraputic cloning (Human reproductive cloning is banned within
Australia), and older blastocysts, embryos or aborted foetuses used for human
theraputic cloning, experimentation on returning pluripotent cells to lower levels
of differentiation or totipotentcy, or germ line research.
Cloning such as that producing Dolly the Sheep, seems to have returned a highly
differentiated cell to totipotentcy. In Dolly’s case, the differentiated cell was an
udder cell. The procedure producing Dolly is known as somatic nuclear transfer.
In this procedure, a cell is starved so that it goes into a resting state known as
G0. Then the nucleus of the egg cell - containing the DNA telling it how to grow is removed and a cell nucleus from the organism to be cloned is inserted in its
place. (The DNA inserted must match the DNA removed, hence at this point in
time, it is only possible to clone females.) The egg cell now has the full DNA to
create a new organism. It is then implanted into the uterus. However, a key bit
of DNA, known as mitochondrial DNA or mtDNA, actually lies outside of the
nucleus and this is not removed. mtDNA is passed through the maternal line and
scientists think it plays a key part in ageing.
It is very important though often not stated in literature, that genotypical or
genetic
identicality
does
not
necessarily
imply
phenotypical
or
appearance/performance identicality. This divergence between genotypicality
and phenotypicality is something science does not understand. Some scientists
are convinced that in time, all human behaviours will be explained genetically,
whilst others take a more critical and wholistic view of humanness.*
Despite genes being identified or associated with phenotypical behaviours and
characteristics such as alchoholism, red hair or mathematical genius, it is very
unclear what this means in actual knowledge of these characteristics and
behaviours and their possible manipulation.#
At the time of writing, perhaps the most promising uses of cloning for humans
are:

To produce cells or body parts to replace those that have been damaged
or worn out, for example growing new spinal tissue, skin or ears.

Spin-off technologies. In the process of developing cloning technologies,
many spin-off technologies have been developed. One such technology is
the ability to very close examine nuclear DNA to permit the selection of
zygotes and blastomeres possessing desirable genes, without damaging
the fertilised cell.
However neither of these functions are without a large amount of controversy
and the following two learning activities focus on these two areas of use and
some of the controversy surrounding them.
For further reading *, A cure for stupidity? and It’s getting the genes to fit, Weekend Australian
March 1-2, 2003. #Warning On Linking Genes and Human Behaviour, The Guardian, October 2,
2002, included in the following resources file.
Oh, give me a clone
Of my own flesh and bone
With its Y chromosome changed to X
And after it's grown
Then my own little clone
Will be of the opposite sex.
A stem cell
The Clone Song
by Isaac Asimov
A stem cell