Biology (Year 12)
Biotechnologists are currently investigating new techniques which utilise DNA, including cloning and stem cell therapy [Note: Stem cell therapy is NOT a part of the ATAR Biology syllabus, and is only used as extra optional study]. The predominant technology which we need to know about is cloning. Cloning is the process of making an identical copy of an original organism. There are two contexts to cloning in biology:
Gene cloning, which utilises recombinant DNA technology - an extracted gene from one organism is inserted into a bacterium, where it reproduces many times
Biological cloning, which involves cloning an entire organism - cloning can make it possible for organisms such as cattle or sheep with desirable characteristics to be produced more rapidly than through normal means of reproduction and selection and is done so via embryo splitting or nuclear transfer
Embryo splitting Egg cells are removed from the donor and fertilised in-vitro via sperm from the male; after the zygote has divided, the coat surrounding the two cells that promotes cell division is removed and the two cells are separated. The two now-separated cells are provided with an artificial coating that acts to promote cell division. Blastocysts (embryos that have just begun differentiating) are implanted into surrogate mothers, and the organisms produced are genetically identical. Nuclear transfer This involves removing mature donor somatic cells from a mature animal and a recipient egg cell from another mature animal of the same species. The donor cells are cultured in a nutrient medium prior to being inactivated, and the nucleus of the recipient egg cell is removed. The intact donor cell nucleus is fused with the hollow egg from the recipient cow via an electrical impulse. The new single-celled embryo is cultured for approximately one week, and then cell division is activated; the developing blastocyst is surgically implanted into the surrogate mother. The offspring is genetically identical to the nucleus donor.
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