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Scientific explanation
In general, cloning means a method of producing organisms with identical sets of genes or
identical genes. Many people are convinced that cloning was born with Dolly the sheep. On
the contrary, vegetative reproduction of plants resulting in formation of clones is very
common. Certain plants, at least in Europe, are in fact clones – e.g., Elodea and certain
species of Reynoutria. In other plants vegetative reproduction is the most common way of
reproduction - planting potatoes or dahlia tubers is an example.
Cloning is also the routine method for molecular geneticists to produce many identical copies
of a gene. Cloning of genes consists of insertion of a particular gene in plasmid, introduction
of the latter in bacteria and cultivation of the bacteria to get great masses of cells. The cloned
gene is then isolated from them in many copies.
In animals the vegetative way of reproduction is regular in groups with simple body design
(e.g. Coelenterata). In animals with more sophisticated body organisation such reproduction
is not possible. However, identical copies are achieved by parthenogenesis. This means that
the female reproductive cell – ovum – starts to develop without an involvement of a male cell
(microspore, sperm). Therefore the resulting genome is a copy of the genome of the female
only. Certain insects (Aphidae) reproduce by parthenogenesis during the most favourable part
of the year and only before winter do they go through the sexual process. Certain fish
(loaches) can also develop just from ovum without the involvement of sperm.
In mammals natural reproduction is sexual, based on fusion of two haploid gametes forming
in this way a diploid zygote where female and male genomes recombine. Therefore genome
of offspring cannot be identical with either parent. In order to obtain identical copies the
diploid nucleus carrying the genome of the “master” must be inserted in the oocyte. Naturally,
the haploid nucleus is removed first.
Cloning was not the aim in the experiment with the sheep Dolly. A transfer of nucleus from
somatic cell in oocyte was performed to answer the question whether somatic cells contain the
entire genetic information of the organism. The sheep Dolly was very apparent positive
answer.
However, in comparison with the vegetative reproduction or with parthenogenesis the nucleus
transfer does not result in an individual with totally identical genetic background. Majority of
genes are carried by the DNA in the cell nucleus, but not all of them. Eukaryotic cells contain
organelles – mitochondria - most probably originating from symbiotic bacteria and generating
energy by using oxygen for aerobic oxidation. They have their own DNA and genes and
reproduce only through division of existing mitochondria because the mitochondrion cannot
be formed from the information contained in the cell nucleus. Sperm does not inject own
mitochondria in the ovum therefore offspring get mitochondria only from the mother. If an
entire donor cell is transferred into an oocyte, its mitochondria do not survive.
Thus, in order to get a totally identical clone, the oocyte and body cell nucleus must be from
the same individual.
Scientific reports recently suggest that oocyte can be developed in vitro from a stem cell.
Based on this achievement of science we may speculate that in the future oocytes will be
prepared from stem cells of the same individual playing the role of a nucleus donor. In such a
case the resulting clone would be exactly identical, from the genetic point of view.
Many pairs of twins originating from one zygote and therefore carrying identical genetic
information were studied. It turns out that they are very alike but still differ in details as well
as in their life history. This is because genes do not determine all features. They can be
“switched on” and “switched off” in different ways due to external factors, they may be even
“silenced” for a long time.
Memory is one of features that are not encoded in genes. Instincts are different. Instincts are
built-in in the structure of neuronal system formed during foetus development. Memory is
created by gradual formation of new neuron connections as a result of learning. There are
regions for various kinds of memory in the brain, e.g., memory for faces, for language, for
motion activity such as walking, etc. Each newborn individual must form neuron connections
the memory is based on. But it is also well documented that adult people who lose memory
due to injury or stroke can resume it by learning.
Therefore there is no scientific background for the statement that memory can be transferred
by cloning.