fig. 1: Sexual reproduction
To ensure that a species will have a better chance of survival, sexual reproduction is often
preferred over asexual reproduction. For example, in human beings, both adults will contribute half
their genes (23 chromosomes) to their child. Through this method of reproduction, no human is
ever exactly the same. The one exception to this is when a couple happens to conceive twins.
Identical twins are exactly the same genetically, and can also be referred
to as "nature's clones".
 fig. 3: Dolly |
The kind of cloning described above is referred to as reproductive cloning. The cloned sheep, Dolly was created through this exact same process. However, Dolly herself was not truly identical to the sheep she was cloned from. The mitochondria in the egg cell still retains some of it's own DNA and so Dolly not only had the nuclear DNA from the cell she was cloned from, but from the egg as well. |
| Recombinant DNA Cloning | Describes the extraction of a DNA desired and placing it in a organism which has the ability to replicate it's genetic material. This is basically the cloning of a gene. |
| Reproductive Cloning | It uses the nuclear DNA of one organism to create another life form that is exactly the same. |
| Therapeutic Cloning | Human embryos are produced and used for research. This technology uses the clones as a method of studying the effects of stem cells and how they can be used to treat disease. Stem Cells have the ability to become any type of cell in the body. It is the hope of many that these cells will eventually be manipulated and be used to replace any damaged or disfunctioning cells in the body. However, the extraction of stem cells are only available in the embryo stage, and this causes ethical problems as the embryo is destroyed once they do this. |
Another way of manipulating an organism's genes is through the method of gene splicing. This technique is done by essentially "cutting" one part of the gene from one organism and transferring the traits contained in the DNA into another plant or animal.
An example of this technology being put to use in our society is the development of insulin. The insulin gene is extracted from the human chromosome and placed into the bacterium. The bacteria is cultured, and human insulin is produced and taken from the bacteria. This proves to be beneficial to us, as diabetics need insulin to treat their condition.
